The 2015 NIGMS Cell Day chat was held on Thursday, November 5, 2015 from 10 a.m. to 3 p.m. EST. Scientists from across the Institute answered questions from students, teachers and the general public.
Joe Gindhart, Cell Day Monitor
Good morning and welcome to Cell Day 2015! Nine scientists are here, ready to answer your questions. We are looking forward to a lively discussion. Questions will be answered in the order received, and then will be posted to the chat as soon as we complete its response.
Co-op High School New Haven, Connecticut: Why do normal cells become cancer cells? Jessica Faupel-Badger: Good morning, Co-op High School! This is a great and complex question. Through many different mechanisms, the DNA of normal cells can accumulate mutations over time. These mutations can then be passed on to daughter cells during mitosis. With successive rounds of cell division, more mutations can accumulate eventually transforming a normal cell into a cancer cell. This process can take decades, which is why cancer is more often seen in older individuals. Our current understanding of cancer arising from our own genes led to two scientists from the United States receiving the Nobel Prize in 1989!
Francis Howell Central High School, Missouri: Is it possible to clone life forms and, if so, are we looking into it? Daniel Janes: The answer is yes. Dolly the Sheep is a famous example. In 1996, the genome of an adult sheep mammary cell was injected into an unfertilized developing sheep egg cell, resulting in the birth of a cloned sheep. The technology has not improved much since then but at least one commercial laboratory now offers to clone pets. Of course, clones of life forms such as humans occur naturally all the time. We call them identical twins!
Francis Lewis High School, New York: What is you annual salary? Darren Sledjeski: Scientists salaries vary widely by field of study and experience. The Scientist magazine released a recent survey that shows you some averages across the USA.
http://www.the-scientist.com/?articles.view/articleNo/44275/title/2015-Life-Sciences-Salary-Survey/. In general, the more education you get the more money you can make. It also varies by the field of study too. But, most of the scientists I know do it because they love science. They love asking questions and doing experiments and finding out how the natural world works.
Co-op High School New Haven, Connecticut: Is there any way a human, plant, or animal can live without any cells? John Laffan: No. All human, plants and animals are made of cells. Without cells they would not be human, plants or animals.
Francis Howell Central High School, Missouri: How can doctors and scientists misread and overlook something in a cell? For example, misreading cancer for something else. Jessica Faupel-Badger: Good morning Francis Howell Central! Cancer is a disease that involves multiple cells - many cancer cells, as well as blood vessel cells, immune cells, etc. Over time, this forms a large enough group of cells that the mass can be detected by various imaging technologies (e.g. X-ray, MRI). However, not everything detected by these methods is cancer. All that is known is that there is a suspicious spot on the image. This can be benign (a group of cells that is not cancerous) or scar tissue from previous surgeries. This is why additional tests may be necessary.
Co-op High School New Haven, Connecticut: Why do we have cells?
Joe Gindhart: Cells keep the inside in (DNA, enzymes, organelles, biochemical molecules) and the outside out (the environment). The concentration of nutrients and other molecules is typically much higher inside the cell, thus making the reactions required for cell function more efficient. Also, cells are a fundamental level of organization for multicellular organisms. Thanks for participating in Cell Day!
Francis Howell Central High School, Missouri: Are there any scientists designing novel organs/body structures or cell types? Donna Krasnewich: This is an interesting question. Some scientists are developing systems that provide the organ function to a person who an organ that is not working correctly. For example, scientists are looking at ways to either transplant functional pancreas cells or create technology that is sensitive, responsive and small enough to replace the glucose monitoring function of a pancreas. Investigators are working on repairing or replacing the function of other organ systems as well. For example, helping improve movement in people who suffer spinal cord injury. When I read your question you made me think about developing new or novel organ systems, that is a really intriguing problem. I think that evolution has done a terrific job of evolving organs that work best to help the species ( in this case humans) survive. If you think about evolution, different human populations are developing novel ways to survive. For example, people that live at very high altitudes have, because of evolution, have developed ways for their bodies and cells to survive with less oxygen. Studies of how different human populations evolve to thrive in their surroundings are teaching us some very, very exciting things about human biology!
Co-op High School New Haven, Connecticut: How'd they create the names for the parts of the cells? Daniel Janes: Great question! Anatomical structures are often named by and for the discoverer(s) of the structure. For example, regions of the pancreas containing endocrine cells are called Islets of Langerhans named after their 1869 discoverer, Dr. Paul Langerhans. Often, the name of the structure can be traced back to Latin or Greek derivations of the structure's function such as the part of the cell called the 'mitochondrion' which is Greek for 'thread-like' in reference to its appearance. To the original observers, mitochondria looked like threads! By the way, this is also true for names of newly discovered species and other scientific terms. New words are coined every day!
Co-op High School New Haven, Connecticut: Do cells ever change? Darren Sledjeski: Yes! Living cells are always in a state of dynamic equilibrium. They are taking in nutrients, metabolizing them for energy, making new molecules that they need and excreting waste products. Even cells that are not actively growing are changing. They need to repair their DNA, make new proteins breakdown proteins that no longer function correctly etc. Cells never stand still.
Co-op High School New Haven, Connecticut: would adding chloroplast to an animal cell allow an animal to do photosynthesis
Zhongzhen Nie: Chloroplast is present in plant cells only. When we introduce any 'foreign' material into an animal cell, the foreign material will most probably get 'lysed' by lysosomes. The lysosomes contain many kinds of enzymes that can digest different biological materials.
East Syracuse Minoa CHS, New York: good morning, I'm a student in central new york. I was wondering how small can a cell be to be classified as a cell
Approximately how small are cells? There are many cell types in the human body that make up the various organs and these can vary greatly in size. For example there are trillions of cells in the human body and over 200 major cell types. Most cells are too small to be seen with the naked eye and must be viewed through a microscope. The largest human cell in diameter (across) is the egg cell, which can just barely be seen with the naked eye. Some of the longest cells in the body are nerve cells. Some nerve cells in your spine can be over 3 feet long as they send their projections from your spine all the way down to your toes.
Co-op High School New Haven, Connecticut: what is the cause of cancer? Jessica Faupel-Badger: Cancer has many different causes. Some cancers are strongly associated with viral infections (e.g. hepatitis B and C viruses, human papillomavirus), others are strongly associated with lifestyle factors (e.g. smoking and alcohol use), so there are known strategies for preventing certain types of cancer. However, many mutations to the DNA arise from our own processes inside our body that by chance accidentally led to the mutations occurring. This is also related to an answer to a previous question - Through many different mechanisms, the DNA of normal cells can accumulate mutations over time. These mutations can then be passed on to daughter cells during mitosis. With successive rounds of cell division, more mutations can accumulate eventually transforming a normal cell into a cancer cell. This process can take decades, which is why cancer is more often seen in older individuals. Our current understanding of cancer arising from our own genes led to two scientists from the United States receiving the Nobel Prize in 1989!
Clarkstown High School North, New York: What is the primary function of the cell organelle, the peroxisome? Also, is it necessary for cell function or can cells live without it? Darren Sledjeski: The primary function of peroxisomes is to breakdown long chain fatty acids. Eventually the breakdown products are converted into carbon dioxide, water and energy in the mitochondria. They also break down reactive oxygen species like hydrogen peroxide. Thus their name.
Co-op High School New Haven, Connecticut: how is cancer different from other deadly diseases? Jessica Faupel-Badger: Many of the cancers we think of - lung cancer, breast cancer, prostate cancer, colon cancer - come from epithelial cells and are a result of these cells proliferating outside of their normal constraints on cell division. Other deadly diseases, such as neurodegenerative diseases, may result in different cell types (e.g. neurons) and result from cell death occurring in these cell populations.
Francis Howell Central High School, Missouri: Our class has read about and discussed iPS cells. What types of research are ongoing with these cells?
Michael Bender: Induced pluripotent stem cells (iPS) are adult cells that have been genetically reprogrammed to an embryonic like state, meaning they can develop into any cell type in the body. Researchers are using iPS cells to model diseases in cultured cells so they can understand what causes the disease and screen for drugs to treat the disease. In the very long run, there is a lot of excitement about using iPS cells for transplantation medicine since in principle, cells could be isolated from a patient, modified, and then reintroduced into the patient without risk of immune rejection.
Co-op High School New Haven, Connecticut: What does one have to do to get named after a cell?
Darren Sledjeski: Interesting question. First, you would have to discover a unique cell or cell type that hadn't been previously described. Then you have to convince a larger group of scientists to accept the name and use it.
Co-op High School New Haven, Connecticut: Is there any possible way to have a cell wall in an animal cell?
Zhongzhen Nie: Animal cells communicate with each other through different structures and proteins on the cell membrane such as GAP junctions and receptors. When you add a cell wall, you will disrupt the communication with other cells so the cell will be dysfunctional and will probably die.
Albemarle Middle School, North Carolina: How many cells are in the human body? Darren Sledjeski: Good question. Scientists estimate there are about 200 cell types and a few trillion cells in the human body. That does not include bacteria, fungi, viruses and mites that live in and on our bodies. These microbes outnumber our own cells several times over. Many of them are important for keeping us healthy. To learn more, check out the Human Microbiome Project at
Pemberton Township High School, New Jersey: Hi, could you tell me anything about a career in scientific illustration or how to obtain a career in scientific illustration?
Donna Krasnewich: The art of scientific or medical illustration is a very important field, especially now. I know that undergraduate and graduate Schools of Art in the United States and across the world have dedicated departments and faculty that are experts in medical and scientific illustration. You can look for these on the internet. Students who have a gift for drawing and love science should seriously consider medical and scientific illustration, they will provide important insight to science as it moves forward. If you haven't looked up Frank Netter on the internet or at the library, please do, his work is breathtaking!
East Syracuse Minoa CHS, New York: Why celebrate cell day? Joe Gindhart: Why not? Cell Day is a lot of fun.
Francis Howell Central High School, Missouri: We recently read about Senescence of cells as we age and their role in cancer. Can you provide more information about this? Shireen Sarraf:
Cellular senescence occurs when cells stop dividing. Every time the cell divides DNApolymerase copies the linear DNA, however, the polymerase cannot replicate the very end of the DNA at each division. Therefore, the linear DNA strand is shorter after each cell division. Telomeres are DNA-protein structures that protect the chromosome ends; when telomeres have reached a critical length after numerous cell divisions, the DNA ends can no longer be properly replicated. Under normal conditions, the cell detects chromosome ends as DNA breaks which it may attempt to repair. If the chromosome ends are too short to be repaired, the cell cycle is arrested through the p53, a tumor suppressor. Because shortened telomeres are dysfunctional, repair cannot occur and the cell enters senescence. The permanent growth arrest evolved in part to suppress the initiation of cancer. In the case of cancer, dysfunctional telomeres may not be detected and the cell cycle progresses. If cell division occurs, chromosome breakage can occur, and propagate in daughter cells. This is a risk factor for cancer.
Co-op High School New Haven, Connecticut: Can radiation affect your cell? and how? Daniel Janes: Yes, radiation can affect the interaction of DNA molecules called nucleotides. Nucleotides interact with each other to form a twisted ladder called a double helix. When exposed to ultraviolet radiation, nucleotides stick together on the same side of the twisted ladder rather than across the twisted ladder as they normally do. This is a cause of mutation as it will affect how the DNA copies itself during cell division. This type of mutation is the primary cause of melanomas or skin cancers in humans. This is a very good reason to limit excessive sun exposure as it is the main preventable source of ultraviolet radiation exposure.
South Lakes High School, Virginia: To what extent does Caspase activity in an organism influence the likeliness of cancer in the organism?
Jessica Faupel-Badger: Caspases are enzymes involved in signaling pathways within a cell that result in that cell undergoing a process of programmed cell death. When caspases are activated within a cell, that same cell undergoes cell death. Cancer is the imbalance of cell death and cell proliferation. Deregulation of caspase signaling or subverting these pathways may skew this balance and allow abnormal cells to proliferate.
Co-op High School New Haven, Connecticut: How long can a cell live outside of the human body?
John Laffan: Given the right circumstances a cell can live for an extremely long time. If we provide the appropriate environment (basically food and support for the cell) a single carefully removed cell can live for a month or longer in the lab. If we consider a cell lines (which are cells that grow and divide outside the body that came from a single cell), we have cell lines that have been around for many decades that show no signs of slowing down.
Co-op High School New Haven, Connecticut: How did life work without the mitochondria? Wouldn't there be nothing living except plants? Darren Sledjeski: Actually bacteria (prokaryotes) do not have mitochondria. In fact mitochondria are closely related to bacteria and evidence strongly suggests that mitochondria were once bacteria. Plants also have mitochondria. Without the evolution of mitochondria large multicellular life would probably be impossible but the plants would be teeming with bacteria.
Co-op High School New Haven, Connecticut: what kinds of cells cause cancer
Jessica Faupel-Badger: There are many different types of cancer and cancer can arise in many different cell types - epithelial cells, neurons, muscle cells. Please visit the National Cancer Institute's list of Cancer Types for more information -
Albemarle Middle School, North Carolina: Do cells come in certain colors?
Shireen Sarraf: Most cells are colorless. However, in order to study them, scientists use dyes to false color cells or attach fluorescent tags to proteins in order to see the cells using microscopes. A few cell types, such as cells with lots of iron, like red blood cells may appear to be red. Melanocytes, cells in the skin, produce pigment that is a determinant of skin color.
East Syracuse Minoa CHS, New York: how log were you in advanced schooling for this career? Joe Gindhart: Great question! I was in graduate school for five years, and then I did additional postdoctoral training for four years. While that seems like a long time, grad students and postdocs do get paid a stipend while they are in training, and PhD students in biology typically get reimbursed for tuition expenses.
Co-op High School New Haven, Connecticut: In class I learned that the Mitochondria was not always part of the cell, Why is that? Why would it do that and eventually stay with the cell to create living things?
Darren Sledjeski: Actually bacteria (prokaryotes) do not have mitochondria. In fact mitochondria are closely related to bacteria and evidence strongly suggests that mitochondria were once bacteria. without the evolution of mitochondria large multicellular life would probably be impossible but the planet would be teeming with bacteria.
Upper Dauphin Area Middle School , Pennsylvania: Are cells wild colors like lime green and neon yellow? Shireen Sarraf: Good morning! Most cells are colorless. However, in order to study them, scientists use dyes to false color cells or attach fluorescent tags to proteins in order to see the cells using microscopes. A few cell types, such as cells with lots of iron, like red blood cells may appear to be red. Melanocytes, cells in the skin, produce pigment that is a determinant of skin color. Take a look at this link for some cool pictures: The Cell: an image library:
East Syracuse Minoa CHS, New York: Good morning, i am a student at ESM in New York, I was wondering how many cells are produced per minute in a persons body?
Jessica Faupel-Badger: Great question! There are different rates of cell division based on the different types of cells and growth of an organism. For example, developing offspring are undergoing cell division at a much more rapid rate than fully formed adults. Within an individual, cells divide at different rates in different organs. Cells lining your intestine turn over every few days.
East Syracuse Minoa CHS, New York: Why is today cell day? Joe Gindhart: That is a great question. We initially planned to have Cell Day on Friday, but many of us have another commitment tomorrow. Cells are important every day.
Co-op High School New Haven, Connecticut: Can we manipulate cells into becoming bigger or smaller? Daniel Janes: Cells become bigger or smaller depending on the ratio of solute to solvent between the cell and its environment. When placed in a solution with a high solute concentration relative to the cell, a cell will shrink by losing water to become 'isotonic' or balanced with its environment. If placed in a solution with a low solute concentration relative to the cell, a cell will swell by taking in water to become 'isotonic.' A fun science experiment can be done by dissolving the hard shell of a chicken egg by submerging it in household vinegar overnight. The vinegar will digest the hard shell leaving only the semi-permeable membrane around the whites and yolk. You can weigh the shell-less egg before and after submerging it into solutions with different solute concentrations (for example, spoonfuls of salt) for a few minutes. By doing so, you can make the egg shrink and grow as it becomes isotonic with its solution. A quick and easy science experiment!
Co-op High School New Haven, Connecticut: would forming a cell wall on an animal cell be possible, and would it protect you from viruses or things that could hurt your cells? Zhongzhen Nie: Great question. viruses get into our cells by hijacking the normal cellular processes such as binding to receptors on the cell membrane to get internalized. Your idea to provide 'additional protective mechanism' for the cell is interesting. However, cell membrane is critical for the normal function of our cells. The communication between cells mediated by cell membrane proteins is critical. If we add a cell wall, we will disrupt the normal function of the cell.
Co-op High School New Haven, Connecticut: Can cells live over millions of years? If yes, How? Shireen Sarraf: Cells cannot live over millions of years. However, some biological material can persist over long periods of time. For example, DNA can be preserved in fossils, allowing scientists to sequence and study the DNA of ancient humans. Scientists can then compare this to DNA from modern humans, allowing us to study evolutionary changes that have occurred.
Co-op High School New Haven, Connecticut: Can you donate cells like you can donate blood? John Laffan: Blood contains cells (red blood cells and white blood cells) so donated blood is donated cells. Also donate organs (kidneys, bone marrow, etc.) are all made of cells, so they are also donated cells. You can also donate a few cells (e.g. a cheek swab) to isolate DNA for a laboratory experiment.
East Syracuse Minoa CHS, New York: Good morning! I'm a student at East Syracuse Minoa, Central New York, and I have a question or two. First, how is bacteria only composed of one cell when bacteria's can prove to be so beneficial, or even so harmful to the human body? Darren Sledjeski: Although most bacteria do not form multicellular structures (though some do) they can still function as a group. Research supported by the NIH into the human microbiome show that bacteria can work together to protect us from disease, help us digest food, enhance our immune system and other functions we have yet to discover. For more information check out
Co-op High School New Haven, Connecticut: what type of cells can you kill? Is it possible to destroy cancer cells? Jessica Faupel-Badger: Great question! There are many different strategies for destroying cancer cells. Scientists are exploring strategies for using the person's own immune system to attack a cancer. There are also strategies that take advantage of cancer cells being rapidly dividing cells in adults where most normal adult cells are not rapidly dividing. Scientists are trying to also find different specific molecular events in cancer cells that could be unique targets for new drugs.
Clarkstown High School North, New York: What is your favorite cell organelle? Michael Bender: There is some difference of opinion on this around the table. Some like the nucleus because it contains the genetic information in the form of DNA, others like the mitochondria because it is the power source for the cell, and still others like the Golgi because it is a beautiful structure.
East Syracuse Minoa CHS, New York: How many different types of cell our there? Zhongzhen Nie: A human body has trillions of cells. These cells can be divided into over 200 different types. There are also 10 times more bacterial cells living in and on our body.
Upper Dauphin Area Middle School , Pennsylvania: Alex S asks: What would life be like if cells didn't have a nucleus? Darren Sledjeski: Life would look a lot like life did for the first few billion years in the history of the Earth. It would be populated by bacteria which do not have a defined membrane bound nucleus.
Co-op High School New Haven, Connecticut: Are cancer genes pasted down from people in your family? Jessica Faupel-Badger: Yes, about 5-10% of cancer is attributed to having a strong family history of a specific type of cancer. For example, there are hereditary forms of breast, ovarian, and colon cancer where the genes are inherited by subsequent generations. There have recently been some very public examples of individuals acknowledging their high risk of cancer due to a hereditary component.
Northeast High School, Florida: Good morning, we are at Northeast High School in So. Florida. Our question is: once a cell has been exposed to a mutagen, can the mutation be reversed in vivo? Daniel Janes: Reversing a mutation is possible in a single cell using state-of-the-art technology but this is not simple enough to be employed as a therapy for several reasons. First, it is almost never apparent in an organism when a mutation has occurred. A mutation begins in a single cell or a handful of cells. Wouldn't it be great if we could be alerted at the moment a mutation occurs? Perhaps future technologies will allow this kind of alert. Second, even if a mutation can be identified at the time it occurs exactly where in the organism that it occurs, for example in a handful of cells in a petri dish in the lab, changing the DNA to reverse the mutation would require the application of very new techniques called CRISPR or MAGE or other DNA-editing techniques. These are very early days for these techniques and, as always, the future of this field of biomedical science in unwritten. This is a great question and suggests science careers of the future. Think about it!
Albemarle Middle School, North Carolina: If cancer is a mutation in cell division can there ever be a cure? Shireen Sarraf: Good question, however, cancer is much more complicated than just a problem in cell division and involves many different mutations in different genes. In order for a cell to become cancerous, it needs to acquire properties, such as the ability to keep growing and avoid death. This initial genetic change then often makes the cell likely to acquire additional mutations and gain further growth advantages. Scientists have made tremendous progress in treating cancer, and a lot of promising therapies have been developed to treat specific cancers/gene mutations that are driving specific types of cancer. For more info on cancer, go to the NIH's National Cancer Institute website at:
Durant High School, Florida: How long can cancer cells live after the body and its normal cells die? Do they die alongside the normal cells? Darren Sledjeski: Cancer cells would die when the body dies because they need nutrients and energy just like every other cell in our body. Scientists have learned how to grow some cancer cells ( and normal cells) outside the body by providing the nutrients and an environment that allows them to grown. They use these to gain a better understanding of cancer and the basic biology of life.
Co-op High School New Haven, Connecticut: How do cells grow? Joe Gindhart: Cells use chemical energy from their surroundings to make molecules like ATP that can be used to power cellular processes like DNA replication, transcription, and translation. The chemical energy can be organic molecules, light, or oxidation-reduction compounds, depending on the type of cell you are interested in studying.
East Syracuse Minoa CHS, New York: What is a biophysicist? Zhongzhen Nie: Biophysicists apply the principles and methods of the physical sciences to study biological problems. Biophysics deals with biological functions that depend on physical agents such as electricity or mechanical force, with the interaction of living organisms with physical agents such as light, sound, or ionizing radiation, and with interactions between living things and their environment. They do cool things such as X-ray crystallography and electron microscopy.
East Syracuse Minoa CHS, New York: What is the point of having different kinds of cells? Michael Bender: Cells are specialized for different jobs in the body. Some cells, like beta cells in the pancreas that produce and store insulin, produce hormones that regulate your body's physiology. Other cells, like skin cells, provide a protective covering for your body, receive and transmit sensation, and control evaporation and help regulate temperature. These are just a few examples -there is a very long list of specialized functions for cells and scientists are still discovering more.
Co-op High School New Haven, Connecticut: What affect does gravity have on cells? Darren Sledjeski: Gravity has many effects on cells. Plants cells use gravity to sense up and down....roots versus stems for instance. It is not clear whether gravity alters an individual cell components. NASA is actively researching this question since it will be critical to know for our future in space.
Cheektowaga Central High School, New York: How do different viruses develop into other? Daniel Janes: Great question! viruses change when their cells acquire different structures on their surfaces. You may have heard of H1N1 virus which is a type of flu virus. The 'H' stands for haemaggluttinin and the 'N' stands for neuraminidase, both structures on viral surfaces. As viruses gain or lose types of 'H's' and 'N's,' the risk they pose to humans and other animals changes. Current hypotheses suggest that the rate of viral evolution is affected by the species that pass the viruses. Viruses may evolve more quickly as they jump from one host species to another.
Co-op High School New Haven, Connecticut: How fast can cancer cells spread? Shireen Sarraf: Metastasis occurs when cancer cells gain the ability to migrate and colonize different tissues or organs in the body. The cancer cells must gain the ability to survive in a foreign tissue and the way in which the individual cancer cells gain this ability will determine how fast the cancer can spread. Some ways in which cancer can spread are locally (into nearby tissues) or via circulation (through the blood stream or lymph system).In order to survive at these new sites, the cells need a blood supply to provide oxygen and nutrients. The rate of angiogenesis (formation of new blood vessels) will also determine the rate of metastasis.
Cheektowaga Central High School, New York: Hello, how are you? It's so typical of me to talk about myself, I'm sorry I hope that you're well. Did you ever make it out of that town where nothing ever happened? Joe Gindhart: Yes! My scientific career has allowed me to live in the Midwest, West Coast, New England, and the South. Rumor has it I will stay in the South for a while.
Durant High School, Florida: What high paying jobs are available with a degree in cell biology? Jessica Faupel-Badger: There are many career paths open to individuals with an interest in cell biology. Cell biologists work in research laboratories, clinical settings, teach in a wide array of educational institutions, or may even be involved in shaping national policies for scientific research. There are many more careers than I could list here. Please also see a previous answer by Darren:Scientists salaries vary widely by field of study and experience. The Scientist magazine released a recent survey that shows you some averages across the USA.
http://www.the-scientist.com/?articles.view/articleNo/44275/title/2015-Life-Sciences-Salary-Survey/. In general, the more education you get the more money you can make. It also varies by the field of study too. But, most of the scientists I know do it because they love science. They love asking questions and doing experiments and finding out how the natural world works.
East Syracuse Minoa CHS, New York: Hi, I'm a student from NY and i have two questions, What is a biophysicist? What is a pathobiologist? thanks for your time :) Zhongzhen Nie: A biophysicist applies the principles and methods of the physical sciences to study biological problems. Biophysics deals with biological functions that depend on physical agents such as electricity or mechanical force, with the interaction of living organisms with physical agents such as light, sound, or ionizing radiation, and with interactions between living things and their environment. A pathologist is a physician who specializes in diagnosing diseases by examining tissue, blood, and body fluids using sophisticated laboratory techniques. Pathologists normally go through residency training after medical school.
Cheektowaga Central High School, New York: What made you want to go into the medical and scientific field for a career? Also what did it take to get where you are now, education wise? Shireen Sarraf: Good morning! Thanks for your question. I wanted to study science, and biology specifically, because to me, it seemed like one of the few fields in which there was the opportunity to discover things which no one had ever studied before. Being a scientist is like being a modern day explorer into the unknown! Education-wise, becoming a scientist takes a good bit of training, including college followed by graduate school (PhD) or medical school (MD). Throughout your schooling, you will have the opportunity to work in research labs, in field studies, or with patients, and learn about designing experiments and analyzing data. Being a scientist is hard work, but very rewarding!
Hello Cell Day participants! We have received more than 400 questions so far. Thank you for your support and interest; we are answering the questions as fast as we can.
East Syracuse Minoa CHS, New York: Why do cells divide instead of actually growing (becoming larger)? John Laffan: Cells usually grow (increase in cytoplasmic volume) before they divide. Otherwise the daughter cells just get smaller and smaller (though is some circumstances that happens as well for a period of time). There is a size range where certain cells types are efficient. If the cell is too small and all the important cellular components will not fit and when they get too big there is not efficient transport around the cell and it dies. There are many cell signals that control cell division so that is happens at an appropriate time.
East Syracuse Minoa CHS, New York: What structures do all cells have in common? Michael Bender: All cells have an outer covering in the form of a membrane, which encloses the cytoplasm containing proteins and nucleic acids such as DNA and RNA.
East Syracuse Minoa CHS, New York: Good-morning, I am a student in a New York central high school. I was wondering if you could answer a question for me. What are the structure and components of DNA? Daniel Janes: DNA is composed of molecules called nucleotides. There are four kinds of nucleotides: adenine (A), cytosine (C), thymine (T) and guanine (G). The organization of these four nucleotides in long chains of DNA determine the information contained by the DNA and passed from generation to generation. A repeating and reshuffled series of only four components (A,C,G & T) may not seem complex but consider that two components (0 and 1) constitute binary code used to store information in almost all modern computer systems!
Cheektowaga Central High School, New York: How many different types of bacteria are there? Darren Sledjeski: Great question! We don't know. Scientists estimate that there are 10,000,000 species of bacteria on Earth. But it is just a guess for several reasons. First, we can not grow all the different bacteria yet. Second, bacteria grow in places we can't easily access, like deep under the earth, under the Antarctic ice cap, deep in the oceans, some even high in the atmosphere, etc.
Cheektowaga Central High School, New York: Is Nyquil an antibiotic? Joe Gindhart: No.
East Syracuse Minoa CHS, New York: Why did HeLa cells grow so abnormally fast compared to other cancer cells? Jessica Faupel-Badger: Just like different normal cells have different rates of cell proliferation, different types of cancer cells proliferate at different rates. This may be due to the type of organ the cancer cell came from (e.g. lung vs. prostate), the growth factors the cancer cells respond to, or the specific mutations in the DNA that may be unique to that particular cancer.
East Syracuse Minoa CHS, New York: Why do u chose to study cells? Darren Sledjeski: Since I was a high school student I have always been fascinated by how cells work. How do they sense temperature? How do they know when to divide? How do they know when other cells are around? How do they cooperate to make me? A million questions that we are still trying to understand.
Co-op High School New Haven, Connecticut: How do people get diabetes? Could it be from eating food that contains too much sugar, or not eating enough food that contains sugar? And are their cells in our body that can show someone is a diabetic? Donna Krasnewich: Clinicians do not understand all of the reasons diabetes develops. There are several major types of diabetes, Type 1 and Type 2. Each of these types has different underlying causes, both genetic and environmental. From the perspective of genetics, there are some genes in our DNA that are not working well in people with diabetes. These genes are involved in keeping the glucose /sugar levels in our blood at normal levels. If these genes don't work well, the cells in the body can't do their jobs to use the energy from glucose correctly. Also, people who have excess weight are at increased risk for developing diabetes. So,there are likely many genes creating a network of signals and environmental factors that work together to lead to diabetes in an individual. This is why we call diabetes a complex trait. The way doctors test whether you have diabetes is that they look at glucose levels in the blood. Doctors can give you a sugary drink and measure your glucose levels, a glucose tolerance test.
Cheektowaga Central High School, New York: What kind of job can you get with a microbiology degree? Darren Sledjeski: There are lots of options! From High School teacher to clinical lab technician to research scientist to Program Director at NIH (my job). For more information check out http://www.asm.org/index.php/scientists-in-k-12-outreach/careers-in-microbiology.
Co-op High School New Haven, Connecticut: If cancer is usually found in older people due to the amount of time it takes a normal cell to become a cancer cell, then why do young children have cancer? Do the cells in their body have anything to do with it? Shireen Sarraf: You are right that cancer is often considered a disease of age. This is because the longer a cell lives, the more likely it is to either accumulate mutations due to errors that accumulate over a lifetime of cell divisions or to experience damage from years of environmental exposure. However, cancer can occur in younger people for a variety of reasons. Children may be born with gene mutations that can be either inherited or occur spontaneously during development (possibly due to environmental exposures) that may predispose the child to developing cancer. Unfortunately, the causes of childhood cancers are often not known. For more information, check out this link:
Co-op High School New Haven, Connecticut: When did you become interested in this field?
Daniel Janes: I knew I liked to think about the way life works at a very early age. Broadly speaking, Biology is interesting even to babies. You can watch a newborn react differently to living and non-living things. It's fascinating! More specifically, I became interested in genetics when I taught a high school genetics lesson for the first time. The elegant transfer of information from DNA to mRNA to protein just made sense to me. It clicked! To my eye, the real answers to the most important questions are biological. Think about it!
Wow! We have hit the 500 question mark.
Jamesville-DeWitt, New York: What is the largest cell? What is the smallest cell? Jessica Faupel-Badger:
There are many cell types in the human body that make up the various organs and these can vary greatly in size. For example, there are trillions of cells in the human body and over 200 major cell types. This does not include bacteria, fungi, viruses and mites that live in and on our bodies. Most cells are too small to be seen with the naked eye and must be viewed through a microscope.
I imagine that the Guinness Book of World Records would list a bird egg as the largest cell, perhaps from an ostrich. However, there are nerve cells that are several feet long, such as the nerve cells that extend from our spinal cord to our toes, the ones that extend up the neck of a giraffe, or the giant axon in a giant squid. Thanks for your question.
Durant High School, Florida: What kind of cells make up the letters on your logo? Darren Sledjeski: C= endoplasmic reticulum, E=mitochondria, L= nerve cell, L=bacteria
Upper Dauphin Area Middle School , Pennsylvania: How do cells keep up with what we are doing everyday? John Laffan: Your cells (except your brain cells) do not know what you are doing. They just respond to what is happening in their immediate environment. Cells produce many signals that go out to the local environment to tell nearby cells what to do. For an example, an injury to an area produces cell signals from that area which recruits cells (like macrophages) to that area and tells the local healthy cells to proliferate and other signals tell damaged cells to destroy themselves.
Co-op High School New Haven, Connecticut: Are there ways that we could make humans able to live off Co2+ H2o & sunlight like plants? Daniel Janes: No. The manufacture of the energy from the components of carbon dioxide, sunlight and water is called photosynthesis. Plants do this in organelles called chloroplasts. Animal cells lack chloroplasts. For this reason, humans cannot photosynthesize.
Co-op High School New Haven, Connecticut: Are we made up of anything other than cells? Zhongzhen Nie: Cells are the functional units of our body. The extracellular spaces are filled with other materials. For example, cells are attached to the extracellular matrix that are critical for normal physiology. Extracellular matrix proteins such as collagen and fribonectin are important research topics.
East Syracuse Minoa CHS, New York: What happens when a cell is damaged? Michael Bender: Cells have a variety of damage response pathways. For example, UV radiation or carcinogens like those found in cigarette smoke damage DNA. Recently, NIGMS funded researchers Paul Modrich and Aziz Sancar shared the Nobel Prize in Chemistry with another researcher for their discovery of enzymes that recognize and repair damaged DNA. The link below describes their work.
G. Holmes Braddock Senior High School, Florida: How does cancer affect cells?
Jessica Faupel-Badger: Hi! Cancer can arise when cells proliferate outside of the normal cues and processes governing when cell division should occur. The mutations or events that stimulate this proliferation can be quite varied. These different events have been mentioned in answers to some of the other cancer questions we have received this morning. You may find some of the other cancer questions in the chat interesting.
Jonas Clarke Middle School, Massachusetts: What is the cytoplasm actually made of?
Darren Sledjeski: Cytoplasm is made up of everything within the cell. For instance, actin and myosin proteins, the organelles , water, nutrients, chemicals etc.
Pemberton Township High School, New Jersey: What are you thoughts on children playing contact sports and the damage it does to your brain related to diseases like Alzheimer's? Donna Krasnewich: The American Academy of Pediatrics has good information on the risks of children playing contact sports
https://healthychildren.org/English/health-issues/injuries-emergencies/sports-injuries/Pages/Sports-Injuries-Treatment.aspx. There is certainly new information emerging about head injury and contact sports. This is not only important to the football players and their families but will also help us to understand the true risk to any child that plays contact sports. Also know that the National Institutes of Health BRAIN Initiative linked at
www.BRAINinitiative.nih.gov plans to explore a better understanding of the Brain. Stay tuned there is a lot to learn!
Jonas Clarke Middle School, Massachusetts: If DNA is the same in every cell in your body, how do different cells do different things? Darren Sledjeski: Great question. You are correct that each cells' DNA is the same (mostly). But not all genes are active in each cell. Genes necessary to make a cell a muscle cell would be on in a myocyte (muscle cell) but off in a neuron (nerve cell). How these genes are turned on and off is a very active area of research among developmental biologists.
Jonas Clarke Middle School, Massachusetts: When you get old, your skin gets wrinkly. Is that because your cells are getting old? Or because your cells are dying?
Shireen Sarraf: The effects of aging in an individual are due to numerous factors, a combination of genetic and environmental effects. The skin is a complicated organ comprised of many different types of proteins and cells. Skin cells produce numerous different factors, including collagen and elastin, two proteins that provide rigidity and elasticity to our skin. As we age, our cells produce less collagen and elastin fibers become thickened and stiff causing our skin to become less elastic, looser, and wrinkly. Exposure to harsh environmental factors (mainly too much sun) can damage the outer layers of the skin, and contribute to accelerating this process. Wear your sun block!
Durant High School, Florida: What makes HeLa cells immortal?
Jessica Faupel-Badger: When the term 'immortal' is used with respect to cancer cells, it is not that the individual cell is immortal. Rather, this is highlighting a property of cancer cells, which is the unlimited ability to proliferate. This means the cells can divide and generate new daughter cells indefinitely. It is these continuous rounds of cell proliferation that give the overall cancer cell type the 'immortal' property rather than any one specific cell being immortal.
Cheektowaga Central High School, New York: What is your favorite research you have done?
Joe Gindhart: I did fruit fly research for almost 20 years. My favorite research focused on understanding how a motor protein called kinesin works in the nervous system. I found proteins that help it attach to the organelles it drags around the cell, which is important for nervous system function in fruit flies and people, too.
Jonas Clarke Middle School, Massachusetts: What part of the human body is made first when an embryo starts to form (what kinds of cells do the first cells become?)
Daniel Janes: Great question! The answer is very complicated as development occurs in several stages. At first, a one-cell stage called a zygote gives rise to two daughter cells called blastomeres. Blastomeres develop into a blastula which develops into a gastrula. The gastrula phase then develops differentiated cell layers called the germ layers of the embryo. As the embryo develops, the germ layers become different structures, giving rise to tissues and organs. It is a long and fascinating process!
Cheektowaga Central High School, New York: How did you know that the career you went into was the one you wanted?
Kris Willis: That's a good question. I guess I always was interested in science, but when I was very young I actually wanted to be a paleontologist! So your interests will probably change as you go through school, and that's ok. The thing that all my friends and colleagues in science have in common, though, is a curiosity about how things work. I think that's actually a trait shared by many people, so anyone who thinks they might be interested in a science career should try to meet and talk to scientists to learn more about it!
Meadowbrook High School, Virginia: why was the cell wall developed?
Michael Bender: The cell wall serves to protect the cell, and to contain the contents of the cell. Cell walls differ a lot -a bacterial or fungal cell living on its own in the soil needs to be constructed differently than the cells of your body that exist within a tissue.
East Syracuse Minoa CHS, New York: Are there any unidentified cells among what we already know? Joe Gindhart: That is a great question! I think we are at the 'tip of the iceberg' regarding what we know about the types of cells in the body and how they work.
Jonas Clarke Middle School, Massachusetts: About how many different kinds of cells are there in the human body? Jessica Faupel-Badger: Great question! There are trillions of cells in the human body and over 200 major cell types.
Van Antwerp Middle School, New York: How do cells know what to do and where to go?
Zhongzhen Nie: In different cells, distinct sets of genes are turned on or off. In addition, cells communicate with each other and receive signals from their environment. For example, a cell can undergo directed migration toward a chemical signal or gradient. Cells have specialized functions such as red blood cells, muscle cells, and neurons.
Francis Lewis High School, New York: What is the difference between the gram positive and negative cells? How is that method useful in order to classify cells? Darren Sledjeski: Gram positive and negative refers to how certain bacteria retain a dye known as crystal violet (purple). In bacteria that have a thick cell wall the dye can get in but not out so they stain purple. Cells that can not retain the dye are stained with pinkish red dye call safranin. Not all bacteria stain gram positive or negative. Other stains and dyes are used to differentiate them.
Upper Dauphin Area Middle School, Pennsylvania: Besides organelles, what else is in the cytoplasm? John Laffan: The cytoplasm is a gel like substance filled with proteins, salts and complex molecules as well as organelles. There are also filaments(like actin and microtubules) to organize and move components around. Some cells have inclusions (like glycogen, starch or lipids for energy storage).
Co-op High School New Haven, Connecticut: how do you become a scientist. I want to become a genetic scientist and I really want to know how did you do that? I bet it was a lot of hard work. I still have 2 years left of school in high school what school would be best for me to apply for college? I'm thinking about Yale, is that good? Kris Willis: That's a really good question. There are lots of good schools where you can study genetics, and lots of good scientists everywhere. The most important thing is to read broadly and look for problems or areas that interest you the most, and then look for labs who study that area or problem. It is a lot of hard work, but when you're interested and enjoy it, it's also fun.
East Syracuse Minoa CHS, New York: Good Morning i am coming from East Syracuse Minoa High School In New York. My question is, How are Genes given to an organism's offspring? Daniel Janes: DNA is the stuff of inheritance. Parents pass copies of their DNA to their offspring. For a long time, the answer to your question was shrouded in mystery. People have known for thousands of years that information is passed from generation to generation. For example, when tall horses mate, their offspring are likely to be tall. This pattern has been understood for a long time but some early scientists thought information was passed from generation to generation in carbohydrates or some other biological molecules. In 1953, James Watson and Francis Crick published the structure of DNA and the manner in which genetic information was contained by DNA became clearer.
Haddonfield Friends School, New Jersey: How thick is a cell wall? Zhongzhen Nie: The gram positive cell wall is usually between 20 and 80 nm thick while the gram negative cell wall is usually between 5 and 10 nm thick.
G. Holmes Braddock Senior High School, Florida: How can we stop cells from aging?
Many scientists are studying aging and ways to manipulate it. Research has shown that most cells and therefore organisms have a defined life span as cells eventually lose the ability to reproduce and replenish themselves. However, researchers are making great strides in understanding the genes that are involved in aging and environmental factors that affect how these genes are expressed. Take a look at these links for more information:
Why Cell Day? It is a great way for you to learn about cells and how they work, and a great way for us to interact with students around the world.
Francis Lewis High School, New York: What are some of the most common genetic mutation? Darren Sledjeski: An interesting question that doesn't have a clear answer. For instance the difference between brown eyes and blue eyes is due to a mutation in an eye pigment gene. The same is true of hair color, height, skin color etc. A very common 'mutation' in the USA is lactose tolerance; the ability to digest the lactose in milk. If you are speaking of genetic diseases two of the most common (in the USA) are cystic fibrosis and sickle cell anemia.
Francis Lewis High School, New York: How is it possible to manipulate one cell into another one? Ex. turning a heart cell into a lung cell? Michael Bender: Until recently, this wasn't possible. Now, techniques have been developed to genetically reprogram an adult cell into a cell with the ability to develop into many different cell types, called an induced pluripotent stem cell. In principle, this would allow a scientist to take an adult heart cell, reprogram it into an iPS cell, and then develop it into a lung cell. The link below has a lot of great information on stem cells, induced pluripotent stem cells, and their potential uses in medicine http://stemcells.nih.gov/info/basics/Pages/Default.aspx (no longer available)
Francis Lewis High School, New York: What are embryonic stem cells and how can we use them in the future? Daniel Janes: Bone cells and nerve cells, for example, are differentiated and do not convert from one type to another by any natural means but stems cells retain the ability to differentiate into a different kind of cell. Stem cells are undifferentiated cells. For that reason, stem cells have the potential to replace or repair damaged cells in living systems. Embryonic stem cells are stem cells that are found in embryos. Stem cells can also be found in adult bone marrow, adipose tissue and blood.
Co-op High School New Haven, Connecticut: Is there ever a case where a human is born without a specific part of the cell (ex. ribosomes, mitochondria. cell membrane)? If so, what would happen? Donna Krasnewich: What an interesting question. Some children are born without correctly functioning organelles in the cell, for example their mitochondria may not make enough energy in the right cells, this makes them ill. Another example would be a child missing a protein that typically is in the cell membrane, for example, an ion transporter in a kidney cell. These children would not have normal kidney function. Proper fetal development requires that all organelles are present.
Van Antwerp Middle School, New York: Is it possible for one type of cell to reproduce a different kind of cell?
Joe Gindhart: Yes, an important part of development is when an undifferentiated cell divides, and then the daughter cell becomes differentiated into one of the many cell types in the body. This is also important, for example, when generating new red and white blood cells.
Co-op High School New Haven, Connecticut: What has to happen to the cells when an HIV Virus attacks our immune system? Darren Sledjeski: The HIV virus attacks the immune cells in our bodies that protect us from viruses. These are called T-cells. It eventually kills them and weakens out defenses against other infections. Scientists are researching various ways to protect us from infection (vaccines), treat and cure those who are infected (therapeutics).
Meadowbrook High School, Virginia: why do plants have a cell wall and animals don't have have one why is that? Zhongzhen Nie: Cell walls help the plant to have a fixed shape and protect it from injury. It helps to keep the plant turgid so that it can stay firm and upright. Because when it enters a high water potential solution, as water moves in, the water exerts turgor pressure on the cell wall and the cell wall thus exerts an opposing pressure to keep water out. Hence cell wall is needed for the plant.
Animal cells do not need cell walls, as they have the cytoskeletal system to protect the organs and cushion them against any external injuries.
Durant High School, Florida: What got you into Cell Biology? What do you do on a daily basis?
Kris Willis: Great question! I got into cell biology and genetics because of a great high school science teacher, Mrs. Dawkins. Over the course of my career the things I do every day have changed a little; now I mostly do a lot of reading, thinking, and writing about really exciting research, but early on I also spent a lot of time looking at cells, counting cells, and doing measurements of the different proteins in them.
Durant High School, Florida: How many cell lines have been created for research? What kind of cells were they? Jon Lorsch: Hi Bianca, THOUSANDS of cell lines have been created by scientists over the past 60 years! They come from almost every organ and tissue type and a wide variety of animals, from humans to insects. They are used by scientists to understand the basic processes of living systems and are also used to produce proteins and other molecules for medical and other purposes. Thanks for your question!
Meadowbrook High School, Virginia: Are all Nucleuses the same size? Joe Gindhart: No. The nuclei of different cell types are different sizes. This is also true during development; for example, a chicken egg is one cell, and then it develops into a chick with many cells.
Medical Academy for Science & Tech. (MAST@Homeste), Florida: Hi, I'm from MAST@homestead and I was just wondering, how quickly do cells multiply? Kris Willis: Good question! Depends on the kind of cell. A bacterial cell might divide in 30 or 45 minutes, but a human cell might take 24 hours or more to divide.
Co-op High School New Haven, Connecticut: Can your emotions affect your cells? or vice versa? and How?
John Laffan: You experience emotions through your nerve cells. They communicate with other nerve cells through neurotransmitters which can change all kinds of processes within those cells. Those nerve cells can stimulate your endocrine system which can release hormones (like adrenaline) which will stimulate other cells (including non nerve cells) to change there current processes. To do the reverse, we could artificially stimulate cells (e.g. with exogenous adrenaline) and the cells would respond with the same type of changes fooling the body to thinks something happened which would effect your emotions.
Cheektowaga Central High School, New York: Favorite research you've done? Donna Krasnewich: That is a GREAT question. I could poll everyone in this room and each of us would have a different answer. Some of us like to work with model organisms like mice or yeast or zebrafish. Some have used really cool microscopes or mass spectrometry or cell culture techniques. Some of us have studied genetics in organisms and humans, each teach us different and exciting science. Chemistry, physics, biology are all moving very quickly and leading us to new discoveries. It is your generation that will answer our most difficult scientific questions. Have fun!!
Jonas Clarke Middle School, Massachusetts: Why isn't the cytoplasm just air? Darren Sledjeski: If humans were labeled with an ingredient list the first thing on it (most abundant) would be water. Water is the solvent that is essential to mediate all of the chemical reactions in our cells. Without water in our cells (or if there was just air) there couldn't be the basic chemistry that is necessary for life as we know it.
Francis Howell Central High School, Missouri: How often do helpful mutations occur in a cell? Daniel Janes: Helpful mutations occur very rarely. The majority of mutations have no affect on the organism's phenotype. In other words, they are neutral mutations. Some mutations are harmful to the resulting organism and very few mutations are helpful, meaning that they improve the resulting organism's chances of survival and reproduction. This kind of helpful mutation leads to a benefit called an adaptation. Helpful mutation is the basis for evolution by natural selection.
Albemarle Middle School, North Carolina: How do cells create hair and nails? Joe Gindhart: Thanks for asking. Specialized cells secrete a protein called keratin, which polymerizes to form hair or nails.
G. Holmes Braddock Senior High School, Florida: What causes abnormal cell growth?
Shireen Sarraf: Abnormal cell growth occurs in a variety of diseases. In the development of cancer, cells must acquire certain properties that allow them to escape the normal surveillance and regulation that keeps cell growth in check. These properties have been defined as “The Hallmarks of Cancer” by cancer researchers Douglas Hanahan and Robert Weinberg. See this link for their review article:
Abnormal cell growth occurs when cells achieve the ability to grow and divide independently of anti-growth signals and to evade apoptosis (cell death). Cells can become immortalized, meaning they can divide beyond their natural limit (see previous answers about telomeres). These changes can occur due to gene mutations that are inherited or caused by exposure to environmental factors.
Meadowbrook High School, Virginia: Depending on the cell, does it have its own representation of color?
Shireen Sarraf: Most cells are colorless. However, in order to study them, scientists use dyes to false color cells or attach fluorescent tags to proteins in order to see the cells using microscopes. A few cell types, such as cells with lots of iron, like red blood cells may appear to be red. Melanocytes, cells in the skin, produce pigment that is a determinant of skin color. Take a look at this link for some cool pictures: The Cell: an image library:
Durant High School, Florida: Mitochondria. The powerhouse of the cell and my body. *end haiku* Thank you
Joe Gindhart: :-)
Durant High School, Florida: What are the ethical problems with using embryonic stem cells for research and what ways could we get past them? Jon Lorsch: Embryonic stem cells are made from embryos (hence the name) and there are many ethical issues surrounding whether embryos should be used to generate cells for medical research or for use in actual therapies for diseases. These issues have led scientists to develop new methods to coax adult cells - for instance from skin - to become stem cells. These are called 'induced pluripotent stem cells' or iPS cells. Induced means they were made to become stem cells by putting some new genes into them. Pluripotent means they can become any other type of cell in the body. This is a very active area of research because iPS cells are still not perfect stem cells and scientists are trying to figure out why and how to make them become 'real' stem cells.
East Syracuse Minoa CHS, New York: Good Morning, I am a high school student from Central New York. What makes each cell different and unique from every other human? Susan Gregurick: Hi and thanks for your question. It's the DNA! but more specifically, it is the DNA that is expressed as proteins at any given time and under different environmental conditions. Even identical twins can have differences, even if we can't see these.
Durant High School, Florida: What interested you in cell biology versus other areas of biology? Darren Sledjeski: Understanding how a cell can do all of things it does (metabolize, grow, sense, respond, attack, defend) has always fascinated me. How does a cell 'know' when it is time to divide? How does it line up chromosomes so exactly to make 2 identical daughter cells? How do they communicate with each other and 'know' how to respond. How do our immune cells recognize a foreign cell and know to attack it? Think of all the amazing things cells can do and ask yourself how does it work? Those are the questions scientists are asking now and we have a long way to go to understand cells.
Haddonfield Friends School, New Jersey: What is the average amount of cells that a human regenerates in a lifetime? Kris Willis: Hi E and R! Wow, complex question. There are trillions of cells in the human body; scientists think there are about 200 major different types. Some regenerate more often than others. For example, red blood cells have an average lifespan of a few months, but white blood cells have an average lifespan of a few days. Over the course of a whole lifetime, that's a lot of cells!
Durant High School, Florida: what kind of stuff do you guys do day to day? Alexandra Ainsztein: As a Program Director, I use my scientific expertise in cell biology to recommend grants for funding, help guide lab researchers through the grant process, and develop new programs (initiatives) to facilitate the scientific enterprise.
Check your cell IQ! Which organelle is known as "the cell's brain"?
The correct answer is: B. Nucleus.
The nucleus is known as the cell's brain because it contains almost all of the cell's genetic material and is responsible for many important functions.
G. Holmes Braddock Senior High School, Florida: Are there any cases in which we can inherit Paternal mitochondrial DNA? Donna Krasnewich: For many years it has been known that the egg contains the mother's mitochondria and the sperm mitochondria does not get transferred when fertilization occurs. In human studies there is some debate about whether passing paternal DNA through the sperm during fertilization is even possible. This reflects evidence in non-human model organisms that sperm may pass mitochondria to their offspring. There are also many individuals with mitochondrial disorders where inheritance is clearly passed down from the mother, this would be clinical or epidemiologic evidence for maternal mitochondrial DNA in their children. However, we all learn things when we ask questions and science is built on the evidence provided by the scientists before. Our job as scientists is to ask the question and remain curious as experiments give us answers. Keep asking questions, keep learning and join scientists everywhere exploring the world!
East Syracuse Minoa CHS, New York: Good-Morning, I am a student from a high school in New York and i was wondering, In your opinion what is the most important scientific discovery?
Jon Lorsch: There have been so many incredibly important discoveries in science that it is impossible to say which one is the most important! Some of my favorites are the discovery that DNA is the genetic material and then the elucidation of its double-helical structure. The discovery of 'restriction enzymes' that can cut DNA at very specific places was also very important. All of these advances allowed the entire biotechnology industry to develop and then the creation of many new drugs to treat diseases. One important thing to remember is that all discoveries in science rest on the work of many, many scientists, usually over the course of decades. Science is truly a world-wide team effort and requires perseverance and patience!
Woods Charter School, North Carolina: When and how do cells make new organelles?
Kris Willis: Good question. To some extent it depends on the organelle, but generally cells make new organelles when they divide. Exactly how they do it is something we're still studying. :)
Durant High School, Florida: How have you specifically benefited from your field of expertise? Do you have any advice for learning students aspiring to be future scientists? Alexandra Ainsztein: I use my scientific expertise everyday. As a Program Director I make funding recommendations and I must understand a broad scope of science. Being a Ph.D. level scientist, also helps me keep in perspective what is considered reasonable progress in the lab and appreciate the challenges that occur in the lab. I read and think about science everyday and that keeps my job fun!
Cheektowaga Central High School, New York: Do you think that scientists being able to change or purposely mutate genes could be beneficial to society or humans in general? If yes, how so? Scientist2 Team23: That's an important question. The short answer is that there are already a lot of examples of benefits from changing and manipulating genes. Being able to do that allows farmers to grow food crops more efficiently, with the use of fewer pesticides. It allows us to make genuine human insulin in cultured cells so that people with diabetes can be treated more effectively. It's enormously helpful to doctors and scientists studying diseases. That's the easy part of the answer. The harder part is that like any tool or ability, it can be used for good or bad reasons. That's why it is important for scientists and everyone else, to understand the science that is being done, and think about the pros and cons of using that ability. For example, some people are concerned that genetically modified foods might not be such a good idea. Others worry that the ability to change genes in people might tempt some folks to try to make changes that might look like a good idea, but could cause long-term problems, or violate their ethical standards. Whether you are a scientist or not, learn about what scientists do, so you can make informed decisions.
Co-op High School New Haven, Connecticut: Can you slice through a cell literally? Joe Gindhart: Yes. Scientists do this all the time when doing microscopy experiments; there are special diamond knives than can create slices just a few microns thick.
Clarkstown High School North, New York: Where do you see CRISPR going in the next 5-10 years? Michael Bender: That's a really good question because there is so much interest in the CRISPR genome editing technology these days. People are excited about the idea that one day, it could be used to correct a mutation in a person and thus cure or prevent a disease. In the nearer term of the next 5 to 10 years, I see more use of CRISPR as a powerful tool to make directed changes in the DNA in cultured cells or model organisms like flies or mice. The technique has already greatly accelerated discoveries in biology in these systems in many laboratories. In the next 5 or 10 years I think we will also see significant advances in understanding how and whether genome editing can contribute to cell-based therapies for human diseases.
Cheektowaga Central High School, New York: Do you think that scientists being able to change or purposely mutate genes of an individual could be beneficial to society? If yes, how so?
Susan Gregurick: Hi Mohtheman. That's a touch question because different points of view around this topic are being discussed right now. We have new tools to 'edit' gene sequences to remove sections that could be related to specific diseases. The benefit to society in terms of deleting genes related to Malaria is great. We as scientists need to consider not only these great benefits to health and disease but also we need to research the consequences of such technology in order to make informed decisions. Here is an interesting podcast for you to consider as you formulate your own point of view:
Durant High School, Florida: Why with so many scientists and researches does the "cure" to cancer remain unknown? Jon Lorsch: Thanks for your question, Allie. One problem is that cancer is not a single disease, but is actually many diseases. Thus it is unlikely that there will ever be a single 'cure' for cancer. We do now have treatments - which in some cases are cures - for a wide variety of cancers. One exciting recent development has been 'cancer immunotherapy' in which the body's own immune system is activated to attack cancer cells. This has proved effective in treating some forms of skin cancer, which previously had been extremely hard to treat. It is also important to remember that we still don't know nearly as much about biology as we need to in order to cure many diseases. There is a huge amount of work still to do. Maybe you should think about becoming a scientist and helping us figure out what we need to know!
East Syracuse Minoa CHS, New York: What is your favorite cell to study and why?
Alexandra Ainsztein: That's a tough question, but I like neuronal cells. They are long and complex in structure, containing a cell body and synaptic junctions. Although neurons have the same organelles found in other higher eukaryotic cells, the structure of neurons make them unique.
Sandak higher institute, Texas: What are the different categories and capabilities of Electron Microscope and how helpful are they? Janna Wehrle: Most EM scopes used these days are 'scanning' scopes--they very quickly raster a beam of electrons much smaller than the sample size back and forth across the sample to create the 2D image. The image may be created behind the sample (transmission EM) or in front (reflectance EM). The most important new EM technique for biology is called 'cryo-EM'--the sample is frozen intact, not dried and stained with toxic chemicals, as in other methods. These methods provide really sharp pictures of essentially healthy cells.
Florence High school, Arizona: Is it possible to have two nucleus' in one cell? If so how? Joe Gindhart: That is a great question. During fruit fly development, the first series of nuclear divisions happen in the absence of cytokinesis (pinching off of cells from each other). At this stage of development, one egg cell has more than 1000 nuclei! There are really cool movies of this on the internet.
Cheektowaga Central High School, New York: How did you discover your field of science? Janna Wehrle: I liked chemistry in high school, but also was interested in medicine. When I discovered biochemistry, I realized it was a perfect combination for me.
Mountlake Terrace HS, Washington: What is gene splicing and how are cells involved? Kris Willis: Hi Mountlake Terrace! This is one of my favorite topics. To use the genetic information in the DNA, the cell copies it to another, chemically related molecule called RNA; in the simplest case of splicing, the cell can use the same length of DNA to make 2 different kinds of RNA. Think of it like molecular scissors and tape, kind of; different parts of the RNA copy can be cut out and the ends stuck back together. The cutting out and sticking together of the RNA is splicing. But it doesn't happen randomly, there are very specific signals in the DNA that direct the splicing molecules and tell them where to cut!
East Syracuse Minoa CHS, New York: Is it possible to recreate someone's genes? Like if someone had the chance of cancer, is it possible to remove that cancer gene? Jon Lorsch: So you definitely can recreate genes. In fact, scientist have machines that can synthesize DNA and a variety of biochemical methods for making DNA with specific sequences in a test tube. What you are suggesting - making a corrected copy of a defective gene and then putting that into a person to cure a genetic disease - is something scientists are actively working on. It's called 'gene therapy.' It's still very challenging to do this, but researchers are making progress and hopefully it will become an important way to treat diseases in the future. Great idea on your part!!!
East Syracuse Minoa CHS, New York: Is your job labor intensive? Doug Sheeley: Depends what you mean by labor, I guess. I spend most of my time talking to scientists about their research, meeting with colleagues here at NIH to make decisions about which research projects we should provide funding for, and writing about science. I don't usually break a sweat at work! Back when I was working in a lab, I spent most of my time standing at a workbench, and while that work isn't too hard physically, it keeps you active. So physically, most science isn't too hard on you, unless you are doing field work as a biologist or geologist or something like that. Scientists do work hard though. Sometimes you stay in the lab all day and night to work on a long experiment. Once when I was in graduate school I didn't go home for three days. Thinking hard about problems you are trying to solve can be pretty tough too. It can be like homework that never stops, but the great thing is that when you solve a problem, you feel terrific. There's nothing like it.
Francis Lewis High School, New York: How many chromosomes do heart cells have?
Joe Gindhart: It depends on the organism. Fruit flies have 4 chromosomes in their heart, while humans have 46.
Jonas Clarke Middle School, Massachusetts: How does the nucleus control the other parts of the cell? Alexandra Ainsztein: Good question! The nucleus is the control center for gene expression. Genes are contained in
chromosomes that are the cell's
nuclear genome. The function of the nucleus is to maintain the integrity of these genes and to control the activities of the cell.
Haddonfield Friends School, New Jersey: Do larger people have larger cells? Joe Gindhart: Probably not, just more cells. However, I'm sure there are exceptions to that rule to be discovered!
Mountlake Terrace HS, Washington: Is it true that hair is made of dead cells?
Janna Wehrle: The part of hair we usually think about ( and cut) is made of a protein called keratin. This protein is made from the outermost hair cells before they die.
Cheektowaga Central High School, New York: What is your favorite animal to deal with/research? Jon Lorsch: My favorite 'animal' (fungus really) for research is yeast. Yeast are eukaryotes (as opposed to bacteria or archaea) just like us and they share many of the same genes and biochemical pathways we have. But they are much easier to grow and you can do all kinds of experiments with yeast that you can't do with humans or other mammals. For instance, you can easily replace a gene in yeast with a different version and see what effect it has. Also, yeast smell better than most mammals (including some people!). And you can make bread with yeast. So what's not to like about yeast? They also make very quiet and easy to maintain pets.
Meadowbrook High School, Virginia: How would plant cells operate without chloroplast? Joe Gindhart: That is an interesting question. Plants without chloroplasts would probably die very early after germination, but plants can live in the dark for short periods of time, using the sugars created during photosynthesis.
Check your cell IQ! Which of the following is not part of a bacterial cell?
The correct answer is: A.Nucleus.
Bacteria don't contain any membrane-enclosed organelles, including nuclei. They also lack mitochondria, Golgi, lysosomes, and many other structures found in eukaryotic cells.
Meadowbrook High School, Virginia: What inspired you to become a scientist? Susan Gregurick: Hi, I absolutely love answering this question, thanks so much for asking! For me, my love of science happened at a really young age, maybe even as early as first or second grade. I loved to imagine 'what would be the highest possible number if we could continue counting' or 'what would happen if we mixed milk with vinegar'. My parents encouraged me, even though they were musicians and couldn't answer many of my questions. My mom even put up with my kitchen chemistry experiments. I found wonderful teachers throughout my education who encouraged me by asking me tough questions and demanding that I don't take easy solutions to those questions. Keep asking questions and keep trying to think of solutions and you are on your way to a great science career. But no matter what your career path is, passion in what you do will enable you to do great things.
East Syracuse Minoa CHS, New York: Hello, I'm a student from East Syracuse Minoa Central High School. I was wondering what are cells made up of? Doug Sheeley: As you might expect, cells are pretty complicated. You can think of them as machines, because they have lots of moving parts that fit together in very particular ways and do specific jobs. Not all cells are exactly the same inside, by the way. A skin cell isn't the same as a brain cell, for example. So, what is in there? Well, like everything in the world around us, cells are made of molecules. The molecules that make up cells are mostly proteins, lipids (lots of different fat molecules), nucleic acids (what DNA and RNA are made of), carbohydrates (chains of sugar molecules), salts, and water. The lipids are mostly for making the cell's outer membrane and some other membranes inside that separate different 'organelles' in the cell - little machines that do specific jobs in the cell, like the nucleus that holds the DNA, and mitochondria that power the cell. The proteins are machines. Different proteins have unique shapes that do specialized jobs- like the different tools in a toolbox. Some of the proteins, lipids, and carbohydrates are like locks and keys that fit together to send a signal.
We have received nearly 1000 questions, and we are answering more than one question per minute. Thank you again for your support of Cell Day.
Francis Lewis High School, New York: What type of cell would be best for studying lysosomes? Alexandra Ainsztein: Significant work has been done in yeast cells; however, with the development of genetic tools for mammalian cells, research in higher eukaryotic cells is increasing.
Durant High School, Florida: If cancer is so common and so many people die from it, shouldn't our average life expectancy decrease? Krishan Arora: Great question! There are different types of cancer. Scientists have been working hard to find causes of these cancer how these originate and find new cures for their treatment. Depending upon what stage these are diagnosed, many can be treated. So, the key is to get the diagnosis early.
Durant High School, Florida: How did you decide that you wanted to be apart of this field of study? Jon Lorsch: When I was 4, a teacher came to our classroom and showed us a cow heart. I thought it was the coolest thing I had ever seen and decided right then that I wanted to be a scientist. In high school I got very interested in chemistry because I had a great chemistry teacher, and I started doing research in a biochemistry lab. Doing research is about solving mysteries that no one has ever solved before in history - how cool is that? I kept doing it in college and then I went to graduate school. Being a scientist is a great career. You should think about it!
Chamblee Charter High School, Georgia: Can a plant cell be circular? Joe Gindhart: We think of plant cells as being shaped like a box, but plant cells are many different shapes. Good examples are the guard cells of stomata and trichome cells on the underside of the leaf.
Durant High School, Florida: Do certain herbs, such as marijuana, help combat cancer? Kris Willis: Hi Durant High School. There's a lot of ongoing research in the area of cancer therapeutics, and a lot of interest in how diet and natural products interact with cellular metabolism. Right now there are many more questions than answers. It's true that a lot of important drugs come from nature, like aspirin and artemisinin; in fact, Youyou Tu just won the Nobel Prize in Medicine for her work on artemisinin, which is used to treat malaria. But it's important to remember that herbs and natural products can also be dangerous - just because something is natural, doesn't mean it's safe.
Meadowbrook High School, Virginia: How does the cell wall provide support?
Joe Gindhart: Its cross-linked structure resists turgor pressure in a manner analogous to how a balloon resists the air pressure inside it.
Francis Lewis High School, New York: Virus's are difficult to detect. Although scientists create vaccines for virus's, how would the scientists create vaccines without knowing the cause of the virus? Would they need to observe the deaths of other victims to create a vaccine for the virus? So they would capture the virus and make it into a vaccine?
Doug Sheeley: That's a terrific question. First, let's talk about what a vaccine is. A vaccine is made of lots of copies of a molecule that stimulates your body's immune system to attack a virus. How does that happen? Well, your immune system recognizes the cells and molecules that make up your body and learns to ignore them. viruses are pretty good at avoiding detection, but they usually do have some molecule on their surface that your body can learn to recognize and watch out for, but sometimes it needs a little help learning how to do that. Scientists look for which virus molecules might make a good target for your immune system, and then try to make a vaccine by copying that molecule. When the vaccine gets injected into your body, your immune system sees a whole lot of the target molecule and that teaches your body to recognize the virus and get rid of it whenever it shows up. Understanding how viruses make people sick helps scientists come with vaccines. Sometimes, as you say in your question, finding the virus that is the culprit is the hardest part. Studying people who are sick does help to do that.
Florence High school, Arizona: why can we have proteins in the place of phospholipids since we already have so many in the cell membrane? Janna Wehrle: Membranes in cells are super complicated structures! The phospholipids do two jobs. They create separate compartments inside cells and between cells and the outside, but they also organize the embedded proteins to create molecular machines. The proteins in membranes do most of the work. Some move molecules into or out of the compartments. Other proteins pick up signals about the space 'outside' the compartment and transfer the information into the cell by changing shape and the selection of proteins they touch inside the cell.
Cheektowaga Central High School, New York: If we donate so much money to cancer research, why is there no definite cure? Susan Gregurick: Hi Jacques, you ask a really good question and I wish that it were just a matter of money. Cancer is just one word to describe a number of complicated abnormal cellular processes and cell growth run amuck. There are cancers for every organ and a number of biological processes, over 100 cancers in all. Although we have been conducting research on cancer for a long time, a single cure for all of the different cancers seems unlikely. We are making progress and early screening with new treatments promise hope in our fight against cancer. Want to see what NIH is doing in cancer, check out this site for Stories of Discovery:
Durant High School, Florida: How are the terms molecule, protein, and gene related in terms of p53? Jon Lorsch: Hi Haley, p53 is a protein. It acts as a 'tumor suppressor' - that is, it helps keep cells from becoming cancerous. p53 does lots of things, but one of them is to bind to DNA and trigger expression ('transcription') of certain genes. Genes encode the information needed to make specific proteins (there is a gene for p53 itself!). A molecule is any set of covalently bonded atoms. So you can have a molecule of DNA or a molecule of a protein. p53 is a kind of protein molecule.
Mountlake Terrace HS, Washington: How are we able to get such clear photographs of cells? Alexandra Ainsztein: In recent years our ability to image cells has increased by improvements academic scientists and industry experts have made of how we fix cells to a coverslip, technology improvements of lens and cameras, and computation used to recognize and remove background signals. Microscopists view objects and areas of objects that cannot be seen with the naked eye. Here is the link to the NIGMS Life Magnified website. Beautiful images to be explored!
Durant High School, Florida: What is the most interesting thing you have learned about cells while studying them? Kris Willis: That's tough. I would say the most interesting thing I've personally learned about cells is how amazingly different cells with identical genetic material can be - there's a lot of phenotypic variation! We know this is partly because there's a stochastic component to the way cells copy DNA into RNA, but understanding cellular heterogeneity is a very active area of research.
Hi @NIH_Bear; we are ready for your questions!
Bolton High School, Connecticut: Do ribosomes contain a membrane? Jon Lorsch: Nope. Ribosomes are made of RNAs and proteins. The RNAs are long and make up the scaffold of the ribosome, whereas the proteins are stuck into it like chewing gum filling up the holes. As you probably know, ribosomes read mRNAs to make the corresponding proteins (protein synthesis or 'translation'). Although they don't have membranes, ribosomes do sometimes attach to membranes - specifically, to the endoplasmic reticulum. They do this when they are synthesizing proteins that are going to be secreted outside the cell or inserted into the cell's membrane. I love ribosomes!!!
Co-op High School New Haven, Connecticut: BYE HAVE FUN ON CELL DAY!!!
Joe Gindhart: Thank you for your support!
Francis Howell Central High School, Missouri: Do you believe in Creation? Or the Big Bang? And why is this? I've been told stories of both ways on how the earth came to be. Thanks! Janna Wehrle: In the realm of biology, scientists are looking at genetic adaptations over long periods of time. This field is called evolutionary biology. Information from evolutionary biology has contributed a lot to our understanding of health and the development of medical treatments and medicines.
Meadowbrook High School, Virginia: Other than science and cells, what other info/ subjects do u need to know? Doug Sheeley: Imagine learning all about a subject and knowing everything about it, but not being able to explain it to anyone. Imagine being really good at something, but you can't get anything done because you can't get along with anyone . One of the most important things you need to do as a scientist is explain the things you discover. You need to be able to organize your thoughts, speak clearly to a group of colleagues, and write well. Scientists do a lot of writing and explaining. Learning how to write well is really important. We almost never do anything completely on our own, so learning how to work in a team is also important. That's not really a school subject, but it's critical. I went to a small liberal arts college where I had to study a lot of different subjects before I went to graduate school and concentrated more on science. I've always thought that studying a lot of different subjects helped me to be more creative as a scientist and recognize unexpected connections. Whatever kind of school you go to, learning about a lot of different subjects will help you be a better scientist.
Co-op High School New Haven, Connecticut: Hello I'm a student of Coop High in CT I was wondering if there was a way to combine avian DNA and Human DNA like they do in the book Maximum Ride? I know it is fiction but, I think that could happen when are able to combine the correct strands of DNA that are similar. Susan Gregurick: Wow, I love the idea that humans could have wings and that's a great series. Human's have had ideas to combine DNA (or genetic material) since Darwin's time. In fact, that's sort of the principle behind grafting in plant species. Tissues from two different plants are joined and they grow together into a hybrid, BUT the new plant has a combination of DNA (and RNA) from both 'parents'. We are still understanding this effect and how this impacts biological processes and diseases.
Jonas Clarke Middle School, Massachusetts: What magnification do you need to see mitochondria? Or DNA? Alexandra Ainsztein: Mitochondria can be see using light microscopy but very little detail will be seen. There are new methods to label mitochondrial membranes and proteins. MitoTracker is fluorescent dye that stains mitochondria in live cells.
Meadowbrook High School, Virginia: Why is the vacuole important? What would happen if the vacoule left the cell? Alexandra Ainsztein: The vacuole acts as the lysosome, which functions in intracellular digestion. In the absence of the vacuole or lysosome the cell has a high likely of disease and cell death.
Cheektowaga Central High School, New York: What do you do on a daily basis? Jon Lorsch: I am the director of NIGMS, one of the 27 institutes and centers that make up the National Institutes of Health. I have a lot of jobs at NIGMS, but my main job is to make sure the taxpayers' money is invested in the best way possible to support important biomedical research. With input from scientists outside of NIH and the scientific staff at NIGMS, I decide which research studies to fund. NIGMS supports over 4,500 scientific studies that are being conducted at universities and research institutes across the country. Many researchers working near you in Buffalo are supported by NIGMS and other institutes and centers at NIH. My job is great because I get to work with really smart people and I help make possible all of the incredible science that is going on across the country.
Cabell Midland High School, West Virginia: Which came first, the chicken or the egg? Joe Gindhart: That's actually a great question! I would hypothesize that the egg came first, as evolution of a chicken-like ancestor would result in phenotypic changes that made a chicken. However, why the chicken crossed the road will remain an eternal mystery.
East Syracuse Minoa CHS, New York: Good morning, I am a student in central New York. How are meiosis and mitosis different? How are they similar? Krishan Arora: Great Question! Cells divide and reproduce in two ways: mitosis and meiosis. Mitosis occurs in somatic cells and meiosis occurs in reproductive cells. The basic difference is that mitosis results in the production of two daughter cells that are identical to the parent cell, whereas meiosis results in the production of 4 daughter cells that differ from the parent cell in chromosome number and genetic components. There also differ in the stages that occur during each process. For example, mitosis is used by single-celled organisms to reproduce; Meiosis is found in sexual reproduction of organisms.
Co-op High School New Haven, Connecticut: Is it possible to make artificial cells? Will they be able to replicate everything a cell does? Susan Gregurick: The answer is a partial 'yes', we can make an artificial cell-sort of. In 2010, Craig Venter and his colleagues successfully synthesized the genome of the bacterium
Mycoplasma mycoides from a computer record, and transplanted the synthesized genome into the existing cell of a
Mycoplasma capricolum bacterium that had had its DNA removed. The 'synthetic' bacterium was viable, i.e. capable of replicating billions of times. The hardest part of this type of research would be creating an artificial cell entirely from scratch, with all new DNA not from a template of an existing bacterium.
Mountlake Terrace HS, Washington: Is it possible use use viruses and cure cancer? Jon Lorsch: This is a great idea! In fact, scientists are working on it. The idea is to engineer viruses to specifically infect cancer cells and then deliver genes or toxins to those cells to kill them. You are already thinking like a scientist!
Durant High School, Florida: So you like adp or atp better? Joe Gindhart: ATP, because its deltaG is -7.3 kilocalories/mole, so it has lots of energy for cellular 'work'.
Cheektowaga Central High School, New York: How do you discover new substances?
Doug Sheeley: There are different ways a substance can be 'new.' Sometimes scientists study plants and animals from all over the world and try to figure out what molecules make a frog poisonous or a plant make a fever go down when you eat it. They do that by isolating the molecules from samples and then once they think they have a pure substance- all the same molecule- they try to figure out what the chemical structure of the molecule is. That molecule is a discovery. It existed in nature, but now we know what it is and we can try to use it. Another way that substances are discovered is by making new molecules in the laboratory. Let's think again about that poison from the frog. Maybe a scientist is hoping it might be a good medicine. They discover the poison molecule's structure, but it turns out to not be quite right for the job the scientist has in mind. Now she knows what it looks like, and thinks of other similar molecules that she could make from scratch that look a lot like the poison but would work better as a medicine. Those molecules are invented rather than discovered.
Francis Lewis High School, New York: How do cancer cells mutate? What causes a mutation? Kris Willis: Hello Francis Lewis High School, great question. Many different things can cause mutations. Sometimes the machinery that makes new copies of our DNA makes a mistake; other times, ultraviolet light or chemicals can damage the DNA. These kinds of errors and damage are happening all the time! Fortunately our cells have a really sophisticated system for detecting and repairing errors and damage, though; in fact, this year's Nobel Prize in Chemistry went to three scientists who study DNA repair. A mutation happens when DNA gets damaged, but isn't repaired. Cancer cells mutate a lot; one of the things that we think happens early on in the process of a cell becoming cancerous is that the DNA repair machinery goes haywire. We're working to understand which mutations occur before that happens - we think they may be the ones that actually cause cancer - from the many mutations that occur after it happens.
Albemarle Middle School, North Carolina: What is a cytoskeleton? Alexandra Ainsztein: The cytoskeleton is the backbone or the scaffold of the cell. Similar to the spine supporting the form of the body, the cytoskeleton supports the structure and shape of the cell. Cytoskeleton filaments include actin, microtubules, and intermediate filaments. These are the structures on which cargos (aka membrane vesicles) are transported to their proper location in the cell. The cytoskeleton is also vital during cell division and development.
Francis Lewis High School, New York: Which cells were probably the first cells on Earth? Alison Gammie: The first cells on earth were a type of bacteria that grow without oxygen.
Bolton High School, Connecticut: If stem cells can turn into any of cell, then if it is used to treat cancer, could potentially turn into a cancerous cell? Joe Gindhart: Yes, one of the potential dangers of stem cell therapy is that the cell could mutate or have other unexpected effects on the organism.
Francis Lewis High School, New York: Is there anyway we can heal a sick cell back to healthy condition? like using nutritious product or having healthy diet? Krishan Arora: Yes, that's correct! Sick cells may be lacking essential nutrients. So, sick cells can be healed back to healthy condition by providing nutritious and healthy diet and products.
Co-op High School New Haven, Connecticut: How do you grow brain cells? Jon Lorsch: To grow brain cells in a dish, scientists have to find abnormal brain cells that like to divide and can live for long periods outside of a brain. This is usually done by taking cells from a brain tumor, because cancer cells divide abnormally and without the usual controls that non-cancerous cells have. Sometimes cells can also be induced to grow in a dish by infecting them with a virus. The trouble is that in both of these cases the cells are not normal brain cells, so scientists are trying to find ways to get brain normal cells to grow. If they can do this it would be a big breakthrough. Stay tuned!
Mountlake Terrace HS, Washington: If all cells have the same DNA, how come the cells differ from one another?
Janna Wehrle: Cell DNA includes not only the 'blueprint' genes for making cell proteins, but also the 'instruction' genes telling when to make certain proteins and when to stop. As a plant or animal begins to develop from a seed, during the earliest cell divisions, some genes are turned off or turned on permanently, in different patterns in different cells. We call this 'differentiation.' Pretty soon cells that will lead to different organs or tissues become more and more specialized, with the same DNA but different instruction sets turned 'on'.
Cheektowaga Central High School, New York: The flagella of human sperm cells are lined with thousands of mitochondria. Why do you suppose this is the case? Joe Gindhart: Mitochondria make lots of ATP, the fuel that the flagella uses to move and propel the sperm cell forward. If you remove the ATP, the sperm cell will stop swimming.
Check your cell IQ! The mitochondrion plays an important role as the cell's ....
The correct answer is: C.Power Plant.
Mitochondria are referred to as power plants because they convert the food we eat and the oxygen we breathe into cellular energy called ATP (adenosine triphosphate).
Francis Lewis High School, New York: What aspect of the cell amazes you that enticed you to pursue in cell studies? Alison Gammie: I am amazed that every time a cell divides a new copy of the DNA is made with very few errors. It is hard to type without making mistakes - imagine how many mistakes we would make if we had to make a copy of our own DNA by hand!
Mountlake Terrace HS, Washington: If a cell is infected, would other cells know? Jon Lorsch: Good question! Yes - cells communicate with each other and an infected cell can signal to other cells that it is in trouble. In particular, cells have ways of telling immune cells that they are infected so that the immune cells can destroy them and prevent further spread of the virus. I guess cells discovered Twitter before we did!
Cheektowaga Central High School, New York: How many cells do you eat everyday? Joe Gindhart: It depends on what I'm eating. Many cells, if I'm eating fruits and vegetables, but not so many if I am eating pretzels and potato chips.
Van Antwerp Middle School, New York: How do cells pass all of their characteristics and abilities to other cells without losing them in themselves? Kris Willis: Hi Van Antwerp Middle School! Really good question. A cell's characteristics are stored in its DNA, and the structure of the DNA molecule is the key to answering your question. A DNA molecule has two complimentary strands that fit together, kind of like two sides of a zipper. When a cell divides, the DNA zipper unzips, and two new new half-zippers are built by the DNA replication machinery, using the original 'zipper' as a template. When replication is finished, the cell has two new whole DNA molecules; one DNA molecule stays with the old cell, and one goes to the new cell, so no information is lost!
Meadowbrook High School, Virginia: What jobs does cell researching offer? Alexandra Ainsztein: There are many and the opportunities are limited by your imagination. Here are a few. Scientists with expertise in cell biology can work in labs at various levels (the head of the lab or staff scientists, technicians - all vitally important for the advancement of science). Industry, patent law, bioinformatics, innovators, administrators at universities or within the federal government such as program directors (my position), and scientific review officers.
Florence High school, Arizona: What happens during brain freeze? Susan Gregurick: Hi! I hate when that happens. Did you know that it actually has a scientific name 'sphenopalatine ganglioneuralgia', which means nerve pain and that is what brain freeze is. The nerves on the roof of your mouth are sensitive to cold and when you rapidly drink (or eat) something cold, and it goes to the roof of your month, those cells up there react and really quickly constrict. Then blood flow to your brain is reduced-causing a feeling of a headache or brain freeze. It takes a little while (like a few minutes) for the blood vessels on the roof of your month to relax and that unpleasant feeling to go away. Want it to go away faster, put your Tongue on the top of the roof of your mouth to warm it up.
Co-op High School New Haven, Connecticut: Is it possible to make artificial cells?
Doug Sheeley: Making artificial cells sounds kind of like science fiction, but there are a lot of folks working on that and they are having pretty good luck. The problem with making a cell artificially is that there are a lot of things a cell has to do to stay alive and eventually divide into other cells. As much as we know about cell biology and biochemistry, we don't know everything, but if you want to make something completely artificial, you have to put all the right parts into it. Accomplishing that without completely understanding what's needed isn't likely to work very well. Scientists have tried to attack the problem in a couple of ways, in a field called 'synthetic biology.' One idea is to start with the simplest version of a cell you can think of and try to make that. Another way to work on this is to make big changes to a cell that will make it do something completely unnatural - something that could only be caused by the changes you made. Progress is being made in both of these areas, but we can't just make any kind of cell we want just from parts.
Mountlake Terrace HS, Washington: If we found single celled organisms on Mars, do you think the would be prokaryotic cells, or eukaryotic? Janna Wehrle: No way to tell--yet. Neither is more likely a priori. Perhaps we'll get a hint, as we study more of the Martian surface.
Jonas Clarke Middle School, Massachusetts: Do you ever extract organelles from a cell to study them on their own? Alison Gammie: Yes! Scientists often extract organelles and study them on their own. It can be tricky to separate certain organelles from each other, but scientists have figured out clever ways to separate the organelles.
Cheektowaga Central High School, New York: How do vesicles move in a cell? Alexandra Ainsztein: Vesicles move along cytoskeletal structures. They attach to molecular motors (for example dynein, myosin, kinesin) and they attaches to the cytoskeleton filament (actin, microtubules) and using energy the motor moves along the filament, bringing the vesicle with them.
Mountlake Terrace HS, Washington: What cells in the human body are not able to regenerate? Joe Gindhart: This is a surprisingly difficult question to answer. As we do more research, we discover that cell types that we did not think could regenerate can do so under specific conditions. This is a very active field of research.
Francis Lewis High School, New York: What do you think is the most important organelle in the cell and why? Susan Gregurick: Since you are just asking my opinion (and I am a computer person) my favorite organelle is the mitochondria, the power plant of the cell! They produce ATP (the energy currency of the cell) and have a neat little 'cell within the cell' shape. They even have their own DNA!
Bolton High School, Connecticut: What causes the organelles to work together? Janna Wehrle: Cell DNA includes not only the 'blueprint' genes for making proteins and building organelles, but also the 'instruction' genes telling when to create, grow, or destroy organelles. In addition organelles can be moved around the cell to bring them together or move them apart. Cells have molecular railroad tracks (called microtubules) and motors (such as kinesis, dynein, myosin) that move organelles where they need to be.
Bolton High School, Connecticut: Is there a reason why phospholipids switch positions? Alison Gammie: Phospholipid switching is thought to be important for many functions, including transport of vesicles within the cell.
Sandak higher institute, Texas: What is cytrochome, what are their functions? Jon Lorsch: Cytochromes are a very cool and important class of proteins. They hold iron-containing heme groups similar to the one found in the hemoglobin in your blood. In hemoglobin the heme is used to carry oxygen. In some cytochromes, they are used to carry electrons. Cytochromes are important in the electron transport chain that takes places in mitochondria and is used to make ATP. Another class of cytochromes is the cytochrome P450s, which can be found in your liver and elsewhere in your body. Humans have over 50 cytochrome P450s! They destroy a variety of molecules in your body, including toxic substances and drugs. They do this by oxidizing the toxic molecules, and some scientists refer to them as 'molecular blow-torches.' How a person responds to different drugs is sometimes determined by the genes they have for cytochrome P450s. Cool, huh?
Francis Howell Central High School, Missouri: Does chromatin sort itself into measurable regions in the nucleus during interphase, even though it is ubiquitously distributed throughout? Kris Willis: Great question, Francis Howell Central! Nuclear organization, or how chromatin is arranged in the nucleus, is a very active area of research. It's a hard problem, because the nucleus is so small, and chromosomes are even smaller. It's hard to use a microscope to see how such small things are positioned in space, because of the Abbe limit; in other words, below a certain size, two separate points look like the same point, because of the physics of light. (Side note, physics is important for cell biology!) But very recently scientists figured out how to build microscopes that show very small things at a much higher resolution; in fact, in 2014 the Nobel Prize in Chemistry was awarded for this achievement. So watch this space, because thanks to these new microscopes we're now learning a lot more about how chromatin is organized in the nucleus. Right now our best hypothesis is that chromatin organization is highly dynamic, which would explain how it can be both organized into specific regions and evenly distributed throughout the nucleus.
Durant High School, Florida: Any fun facts about cells you can share since we are celebrating cell day? Joe Gindhart: We have answered more than 100 questions so far; there are lots of interesting and fun facts about cells. You can see the answers by reading the chat. Thanks!
Francis Lewis High School, New York: How can the manipulation of cells help benefit today's world? Is there any specific cell manipulation that can save lives? Doug Sheeley: There are a lot of examples of biotechnology - using living cells as technology to do a job. Sometimes it's as simple as using cells as little factories that read DNA instructions to make protein machines. To change what the factory makes, sometimes you just have to put a new set of instructions (a new piece of DNA) into the cell and let it do its job. Lots of medicines are made that way. There are more complex things you can do. For example, maybe you want a plant to be immune to the effects of a weed killer. That's useful for farmers, because they can kill weeds while letting a food crop grow just fine. There are a lot of changes that can be made to cells so that scientists can study them. Inserting instructions that will force the cell to make a different version of a protein- one that glows green, for example- lets the scientists follow the protein around inside the cell and learn more about how it works. There are more ways to manipulate cells than you can think of, and more are coming every day.
More facts about cell 'numbers':
Durant High School, Florida: How are you doing today? I bet you haven't been asked that yet? Joe Gindhart: I am great! Thanks for asking.
Mountlake Terrace HS, Washington: How long is the average lifespan of a cell? Kris Willis: Hi again Mountlake Terrace! That very much depends on the kind of cell. For example, red blood cells live on average for several months, but white blood cells only a few days.
Bolton High School, Connecticut: How many cells die in a day? Lee Slice: Well, I assume you are referring to people but millions of cells in your body die and are replaced each day. Your skin cells and the cells in your gastrointestinal tract are replaced every 3 to 4 days.
Francis Lewis High School, New York: I heard that there was this lady called Henrietta Lacks and they said that once she got cancer they took cervix cells. Why did she have immortal cells that never died and kept growing? Was it caused by the tumor?
Krishan Arora: Great question! Henrietta Lacks had cervical cancer. Cancer cells are transformed and mutated, and have tendency to undergo uncontrolled mitotic cell divisions causing unregulated growth. When these cells are isolated and kept in culture media with nutrients they can keep dividing. These cells are now available as immortal cell line and are used in scientific research.
Cheektowaga Central High School, New York: What do you think about the over use of antibiotics Jon Lorsch: Antibiotics kill bacteria. They do this by blocking different pathways that the bacteria need to live. For example, penicillin interferes with a bacteria's ability to make its cell wall, causing the bacteria to explode (!). Bacteria can evolve ways to become resistant to specific antibiotics. Often, the gene for the target of the antibiotic gets mutated and the target is no longer sensitive to the drug. If antibiotics are overused, it gives bacteria more chance to mutate or change in other ways and become resistant to the antibiotics. Then, the next time the drug is used, it might not work. Interestingly, Alexander Fleming, one of the discoverers of penicillin, predicted that resistance would emerge and become a problem. Unfortunately, he was right and now scientists are working hard to find new antibiotics that bacteria are not resistant to and that will be harder for them to escape.
East Hartford High School, Connecticut: How do scientists know what goes on in a cell and how they function? Alison Gammie: Scientists use many methods to study how cells function. For example, there are many types of microscopes that allow scientist to see structures within the cells. Scientists are also able to tag parts of the cell with fluorescent markers and follow their movement within the cell. Sometimes scientists break open cells and study the individual parts.
Here are some nice links to stories about colors and cells:https://biobeat.nigms.nih.gov/2013/12/cool-images-holiday-season-cells/,
Bolton High School, Connecticut: What causes cells to mutate? Jon Lorsch: Mutation is when a cell's DNA changes. This can sometimes produce a new behavior in the cell ('phenotype'). Occasionally, these new behaviors lead to diseases such as cancer. Mutations can be caused by a number of different things. Radiation - including UV light from the sun - can cause DNA damage and mutation. Chemicals - including those found in tobacco smoke - can also cause mutations. Sometimes mutations just happen randomly, when the enzymes that copy DNA make a rare mistake. Luckily, we have enzymes that scan our DNA looking for mistakes and fixing them. This is called DNA repair, and two scientists (whose work was funded by NIGMS!) won Nobel prizes this year for figuring out how it works.
Jonas Clarke Middle School, Massachusetts: Do you think there are organelles that scientists haven't discovered yet? Susan Gregurick: Since we have some really amazing technologies to see what's on the cell membrane and what's inside the cell, and at a pretty high resolution too, I think that we have seen most of the organelles that there are. However, just seeing an organelle is not the same thing as understanding it's function within the cell and all the ways in which that function can be altered and under what conditions. I would say given the recent papers in Cell and Cell Research, organelle function is still an undiscovered country. Keep discovering!
Here is another great fact sheet about cells:https://www.nigms.nih.gov/education/Pages/FactSheet_Cells.aspx
Check your cell IQ! What is apoptosis?
The correct answer is: B. Planned cell death used by the body to sculpt fingers and toes and to eliminate cells that contain damaged DNA. Apoptosis, also called programmed cell death, is critical for shaping our bodies before we are born. It also protects us against cancer by ridding the body of genetically damaged cells.
Jonas Clarke Middle School, Massachusetts: Is there any organelle a cell can go without?
Lee Slice: Generally, cells have evolved to contain the organelles that are needed for that cell to do its specific job. If you could specifically remove an organelle from a cell, then that cells function related to that organelle would be missing and the cell would not be healthy and might die as a result. However, some cells get rid of things as they become specialized. Red blood cells that carry oxygen loose their nucleus and do not divide. Mature red blood cells only last a week or so before they are removed from circulation.
Jonas Clarke Middle School, Massachusetts: What happens to a cell in your body after it dies? Stefan Maas: That's a great question. Usually, the cell is being dismantled as it dies; depending on the particular death pathway that the cell is using (there are many variations), it might be digested from within until the final left over material is taken up by immune cells and further broken down. Alternatively, it might burst early on with the content of the cell, as well as the envelope getting taken up by special immune cells that will then digest its constituents. At the end, many of the molecular building blocks from these dead cells will be re-used.
Mountlake Terrace HS, Washington: IF a host dies does the cells die with it? Janna Wehrle: For multicellular plants or animals, if the overall organism dies, the systems for taking in and circulating oxygen and nutrients will slow and then stop. Eventually the individual cells will die, but it may not be right away. Recall that we can cut a slip from a plant after it's been cut down and root it in water-if we do it quickly enough.
Cheektowaga Central High School, New York: Can drugs affect your chromosomes? Lee Slice: Yes, there are many drugs that can bind to DNA and can interfere with DNA replication. This can result in chromosomal mutations, which can lead to cancer.
Albemarle Middle School, North Carolina: If a cyto skeleton gets infected can it kill you? Joe Gindhart: Yes! For example, rabies virus travels along microtubules to the cell nucleus, where the virus replicates, leading to the symptoms associated with rabies infection.
Mountlake Terrace HS, Washington: Do you guys volunteer to answer these questions? Joe Gindhart: Yes, although we have tasty snacks.
Francis Lewis High School, New York: How do carcinogens affect cells? I understand that carcinogens are cancer causing agents, but can you describe the entire process? Kris Willis: That's a multifaceted question, actually. Different carcinogens work in different ways, and we don't fully understand how the whole process works at the molecular level for all carcinogens. One carcinogen we understand pretty well is ultraviolet light. You probably know that DNA has four nucleotides - A, T, C, and G. Some places in the DNA sequence, there are two T nucleotides in a row. Ultraviolet light can trigger a chemical reaction that creates a covalent bond between those two T nucleotides; if this damage isn't repaired, it becomes a mutation, which can be carcinogenic.
East Hartford High School, Connecticut: What major experiments are being done on cells today? Jon Lorsch: Cells are incredibly important in biomedical research! Most researchers studying basic biological processes or diseases work with cells. Sometimes they grow them in dishes or flasks to study them and sometimes they study them in animals. One exciting area of research is induced pluripotent stem cells, also called iPS cells. iPS cells start out as cells from an adult - for instance your skin cells. Scientists have figured out a way to add a specific set of genes to these cells and turn them into stem cells that can become many different kinds of cells, such as a kidney or liver cell. Understanding how this happens is very important, so we can make it work better. The hope is that these iPS cells can eventually be used to help repair damaged or non-functional organs in people. Maybe one of you will be the researcher who makes this happen!
Bolton High School, Connecticut: How do stem cells from umbilical cord blood benefit a child? Alison Gammie: One important use for stem cells is to replace diseased or damaged cells. Stem cells are also useful for scientists to test drugs.
Cheektowaga Central High School, New York: Can you explain why biologists claim there are more prokaryotic cells inside the human body than there are eukaryotic? Alex Valm: That's a great question. One that we have been asking ourselves for a long time. It is estimated that there are 10 times more prokaryotic cells in the human body (mostly in the gut) than there are human cells. This observation comes initially from a study in the mid 20th century where scientists labeled human gut contents with a fluorescent stain that binds to bacterial nucleic acid, called acridine orange. The scientists then estimated the total number of bacteria in the whole body based on the known volume of the gut. Modern methods of DNA sequencing now suggest that there are 100 times as many prokaryotic genes in the human body than there are human genes. You can learn more about this research here: Human Microbiome Project at
Haddonfield Friends School, New Jersey: Do all living things have cells? Alison Gammie: Yes. All living things have cells. Some living things are just one cell (for example a bacterium is a single cell).
Haddonfield Friends School, New Jersey: Is there such thing as too many cells? Lee Slice: Yes, the number of cells in our bodies is regulated and if you have too many of a specific cell type, then that can lead to disease. Cancer is a disease where cells continue to divide and crowd out normal cells so that the normal cells can no longer do there job.
Florence High school, Arizona: Why is 'gel electrophoresis' important for deoxyribonucleic acid (DNA) testing in criminal cases? Doug Sheeley: Everyone's DNA is different. If you find a way to analyze DNA left behind by criminals you can identify the person who was there. DNA is made of very long strings of four similar molecules that fit together like links in a chain. Let's just call them A, T, C, and G. DNA sequences can be written like this: AAAGCTAGGGCCTTAAACCTTGATCCTGA... Imagine that going on for thousands of letters. The DNA can be cut up into smaller pieces using special protein scissors called enzymes that only cut when they recognize a certain sequence of letters. Scientists have identified the enzymes and companies make them and sell them. The short pieces of DNA the enzymes make can then be separated from each other pretty easily by passing them through a gel. Gels are porous, so water goes right through. DNA takes longer than water because it's bigger. The bigger the piece of DNA, the longer it takes. Everyone's DNA can be cut up and analyzed with a gel to make a pattern of DNA pieces of different lengths. Everyone's patterns are different. Comparing patterns from a crime scene and from a suspect tells you whether that person left the DNA at the crime scene.
Francis Howell Central High School, Missouri: Is it possible for a cell to stop dividing in the middle of a phase in PMAT? If so what does that cause in the body? Stefan Maas: While the main cell cycle checkpoints cells use to interrupt the overall process are positioned in between the PMAT phases, cells might stop cell division (and may be forced to do so) if they suffer damage that prevents its progression. The cell might die and get removed by the immune system.
Thank you for your interest in Cell Day. We have received more than 1400 questions, and the ten scientists are working as fast as we can.
Sandak higher institute, Texas: Some laboratories culture bacteria without biosafety cabinet and with no resulting contaminations, how is that possible? Alex Valm: Although bacteria are present in the environment: on surfaces, on our bodies, in the air, it is possible to culture bacteria on the laboratory bench using good aseptic technique. Usually we will light a Bunsen burner, the heat from the flame creates an air current that lifts the air up. One can open a flask of media under the flame and the air will flow away from the opening, not into the flask. Another important part of aseptic technique is working quickly: by only having media in the open for brief periods of time it make it less likely that they will get contaminated. It takes a lot of practice but once you learn aseptic technique it's possible to culture bacteria on the bench.
Mountlake Terrace HS, Washington: How quickly do cells replicate? Alison Gammie: The cell cycle varies depending on the organism, stage of development, and the conditions in the environment outside the cell. Human cells typically need about 24 hours to divide, but certain bacterial cells can divide in 20 minutes. Cells in the fertilized fruit fly egg divide every 8 minutes, but cells in the larva and adult take much longer to divide. A type of bacteria called
E. coli divide quickly if growing in rich nutrient conditions, but they divide much more slowly under crowded conditions or when nutrients are limited.
Mountlake Terrace HS, Washington: "eukaryote" includes what cells? Joe Gindhart: Eukaryotes are cells that contain a nucleus.
Bolton High School, Connecticut: What is your opinion on whether or not viruses are alive? Alex Valm: Great question. Scientists generally agree that viruses are not alive because they are obligate intracellular pathogens. Although they have a genome consisting of nucleic acid, viruses require a host cell in order to reproduce. Although they are biological entities containing nucleic acid, protein and sometimes a lipid membrane, they are usually not considered to be alive.
Check your cell IQ! Which of the following is not involved in cell movement?
The correct answer is: C. Vesicles.
Flagella, cilia and the cytoskeleton all help cells move. Vesicles, on the other hand, transport materials into, out of and within cells.
Check your cell IQ! The largest human cell (by volume) is the egg.
The correct answer is: A. True.
Human egg cells are about the size of the period at the end of a sentence. Other cells are much smaller, and invisible to the naked eye.
Cheektowaga Central High School, New York: How often does a cell divide? Krishan Arora: Great question! Well it depends on cell type. In humans, there are a lot skin cells to replace, making cell division in skin cells so important. Other cells like nerve and brain cell divide much less often. Whereas, bacteria such as E. coli divide every 20 minutes.
Bolton High School, Connecticut: What steps are required in "molding" a stem cell to have characteristics needed to treat the intended disease/condition? Stefan Maas: The stem cells, which generally are able to be 'molded' into many different cell types of the body, need to be directed to develop into that kind of cell that is damaged or dysfunctional within the disease/condition that treatment is needed for. For example, if one wanted to treat a neurodegenerative disease, such as Parkinson's Disease, the stem cells should be induced to develop towards a neuronal type of cell; and even more specifically to the kind of neuron that is specifically affected; dopaminergic neurons in the case of Parkinson's.
Bolton High School, Connecticut: how do you know the texture of a cell and what a cell looks like? Paula Flicker: Several different types of light and electron microscopes can be used to look at cells and get a sense of the texture of the cell. The cell or portion of a cell can be labeled to distinguish parts of the cell and watch movement of the cell or within the cell in a light microscope. How fast probes move in the cell gives information on the inside texture of the cell. An atomic force microscope is a microscope that pokes at the surface, such as the surface of a cell, to get a measure of the height of the cell and thus generate a map of the surface of the cell, a topographic map of the surface, which would give an idea of texture of the cell surface. Electron microscopes can be used to look at cells or portions of cells at higher magnifications than can be achieved in a light microscope; however in the electron microscope the sample is either frozen or dried so that movement cannot be watched. A scanning electron microscope can be used to look at the surface of a cell. You can see some light and electron microscopic images via the following link:http://www.denniskunkel.com/.
Francis Lewis High School, New York: Are cells restricted by anything? What are their limitations? Alison Gammie: Cells need nutrients to function and divide. Without proper nutrients, cells don't function properly and sometimes they stop growing. Cells also respond to stress - for example temperature extremes, toxins, and mutagens. Sometimes these 'stressors' cause the cells to stop dividing.
Cheektowaga Central High School, New York: How do you think cancer prevention / detection / removal will change throughout, maybe, the next few years? Doug Sheeley: Treating cancer has gotten a lot better as doctors and scientists have learned more about how cancer cells work. A lot of cancer treatments are pretty hard on the normal cells in a person's body, not just the cancer. That can limit the amount of treatment a person can receive without dying just from the treatment. That's a big problem. Also, treatments don't always work for everyone they are used on, because people's cancers are different from each other. So, discovering exactly how the cancer cells work and how one person's cancer is different from another one does solves two important problems. Treatments that are more specific for the cancer cells don't cause as many side effects that hurt patients, and they are also way more effective. There are more and more examples of cancer treatments like this, that work really well and are not as toxic, and more are coming. Another improvement will be in detecting cancer, using better imaging (like mammograms) that show tumors, and blood tests that will detect cancer before it would show up in an imaging test. Earlier detection and better treatments are both coming.
Francis Lewis High School, New York: Good morning! How does cells recognize other substances or other cell? For example white blood cells recognize pathogens, T cells recognize allergic substances. And NK cell recognize cancer. Those cells recognize harmful substances and destroy it. How? Joe Gindhart: The way that cells recognizes extracellular cues like signals and other cells depends on whether the signal can diffuse through the plasma membrane. Some molecules, such as nitric oxide and steroid hormones, can diffuse into the cytoplasm and/or nucleus to affect the function of an intracellular protein. Other signals, such as insulin, bind to receptors on the cell surface.
Meadowbrook High School, Virginia: Would the cell survive just on the glucose, without the ATP formed by mitochondria? Darren Sledjeski: Nope. ATP is the essential energy molecule of cells. Cell metabolism is geared to producing ATP from glucose.
Cheektowaga Central High School, New York: How close are we to curing cancer? Lee Slice: That is difficult to say. NIH has funded cancer research for over 50 years. We have learned a lot of basic biology and cancer biology and have learned effective treatments for certain types of cancers but there is still a long way to go before we can cure all cancers. It is a long process of research and drug discovery and clinical trials. But the goal is achievable. Remember, in the span of just 70 years, we went from learning how to fly to landing a man on the moon.
Cheektowaga Central High School, New York: If you're deciding between two jobs in the medical field, how do you know which you should pick? Janna Wehrle: I'm not sure if you're thinking about medical practice vs. medical research? Or what kind of research? I originally thought about both medical practice and research, but chose the research path when I discovered I like chemistry and solving puzzles. A major choice point is whether interacting directly with patients is a major part of what you enjoy. Within research areas, think about any personal interests--diseases, etc. Also what kinds of tools you like--mostly computers? microscopes? lasers? Participating in a research experience at a college or university near you can be a good way to see how different types of activities 'feel.'
East Hartford High School, Connecticut: Have scientists created robotic cells? Charles Edmonds: Very interesting question. It depends what you mean by robotic. If you mean R2D2 maybe not. But if you look at the constituents of cells, the nucleus, mitochondria, a chloroplast from a plant cell....everything at sufficiently high resolution under a microscope, under an electron microscope, right down to the molecular level by X-ray crystallography methods you will see beautiful and wonderfully complicated machines. For example the nucleus DNA is replicated by a complex of molecular machine consisting of special proteins and nucleic acids. And the list of examples goes. This is a the whole field of structural biology. Scientists who study these machines have learned enough to begin redesigning these molecule machines to make them easier to understand, remodel them using special genetic methods make them work more efficiently. So, I guess the answer is yes, almost.
Francis Lewis High School, New York: Can cells be affected by some of our daily habits? Alex Valm: One of the hallmarks of biological organisms including humans is their ability to maintain homeostasis when the environment is changing around them. Cells in the human body are affected by our daily habits. For example, when we eat a meal, certain cells in the stomach are stimulated to release digestive enzymes. Cells in the liver are specialized for neutralizing toxins that we might encounter. When it's cold certain cells in the body are stimulated to generate heat. These are just a few examples.
Mountlake Terrace HS, Washington: If two viruses infect you at the same time, will those to viruses work together to infect your body, or will they work against each other over domination to see who gets to infect your body? Darren Sledjeski: They could or they could interfere with each other. It depends on the viruses. When bacteria get infected by some viruses they become resistant to infection by other viruses. In humans there exist helper viruses (Hepatitis B) that helps Hepatitis D virus to infect.
Mountlake Terrace HS, Washington: Can any cell type be reverted into a stem cell, or only some kinds? Stefan Maas: That is a very good question and one for which there is no definite answer. Mostly though trial-and-error, researchers have found treatment protocols to induce stem-cell like properties in certain cells. Also, in some disease states, such as cancer, there have been reports that suggest that certain cells are more prone to revert to a stem-cell. Since it is not understood well yet how that process actually works, it is not possible to say if there are some cells that are under no circumstance able to develop back to a stem cell. One exception though would be red blood cells, which loose their nucleus on the way to become a mature red blood cell; and without a nucleus, there is no way to go back.
Mountlake Terrace HS, Washington: Do cells make decisions based off of contact with another, or with chemicals? Krishan Arora: Great question! Cell-cell contact and interactions refer to the direct interactions between cell surfaces that play a crucial role in the development and function of multicellular organisms. These interactions allow cells to communicate with each other in response to changes in their microenvironment. These can occur through protein protein interactions and also via release of chemicals such as neurotransmitters.
Mountlake Terrace HS, Washington: If we could feel a cell (it was big enough for us to hold), what would the texture be like? Would different cells feel differently? Paula Flicker: A cell would feel a bit like a squishy fried egg with a hard cooked yolk. The nucleus is stiffer than the cytoplasm. Different cells would feel differently. A single cell might feel differently through its cell cycle. For example, as a cell moves it makes contacts with neighboring cells and makes protrusions that would vary in in texture.
Bolton High School, Connecticut: Does mitochondrial DNA have the same bases and structure as regular DNA or is it completely different? Darren Sledjeski: Yes! In fact mitochondrial DNA is derived from an ancient bacterial ancestor. But, the DNA is all the same.
School of the Osage High School, Missouri: What's the difference between animal cells and bacterial cells? Darren Sledjeski: Animal cells are eukaryotic. They contain membrane bound organelles like mitochondria, nucleus, chloroplasts...etc... bacteria are prokaryotic and are much smaller (in fact about the size of an organelle) and do not contain the specialized membrane bound organelles.
East Hartford High School, Connecticut: What subjects do you have to take in college in order to be a cell scientist? Paula Flicker: You can take cell biology courses in college. It is very helpful to study chemistry, biochemistry, math and basic physics.
Bolton High School, Connecticut: What are the two types of endoplasmic reticulum? Alex Valm: When cells are observed through the microscope, we can see two obvious types of endoplasmic reticulum (ER). The rough ER is close to the nucleus and looks rough because there are many ribosomes on the ER membrane. This ER is specialized for synthesizing proteins that are either secreted or inserted in the cell membrane. The other obvious type of ER is called smooth ER because it does not contain ribosomes. This ER is specialized for folding and modifying proteins before they get to the Golgi apparatus as well as calcium homeostasis and storage. New evidence suggests many more function of the ER including a role in fission and genesis of other organelles including mitochondria and endosomes.
West Prairie Middle School, Illinois: Why are cells called cells? Darren Sledjeski: When Robert Hooke looked at life under a microscope in 1665 he noticed membrane bound structures that looked like the rooms (cells) that monks slept in in monasteries.
St. Charles Borromeo School, New Mexico: How does UV radiation cause cancer cells? Lee Slice: Ultraviolet radiation can and does cause cancer, especially skin cancer. UVA (longwave length) and UVB (shortwave length) can age and damage skin that results in sunburn. This can result in skin cancer by causing mutations in the skin cell chromosomes. These mutations accumulate and can result in uncontrolled cell division, which results in skin cancer.
Check your cell IQ! During the S phase of the cell cycle
The correct answer is: D.DNA is replicated, or synthesized, prior to cell division. During the S phase of the cell cycle, DNA is replicated, or synthesized, to prepare for cell division.
West Prairie Middle School, Illinois: How is the cell first created? Stefan Maas: I will assume that you are asking about the very first cell that ever arose during early evolution of life on earth. Unfortunately, when it comes to the origin of life on earth and evolution of the first cell, there are no fossils to uncover that could be used to reconstruct the individual steps. However, there are theories and models of how the first biological molecules arose and how they might have formed the first cells. One of these models is the 'RNA world', which assumes that RNA molecules were the first (before DNA and proteins) establishing molecules that were able to evolve to the first 'primordial cells', which combined a number of RNA molecules each with different roles to make up a functional entity that was able to copy its information and divide.
Imagine International Academy of North Texas, Texas: Imagine International Academy of North Texas- How fast is cell transport from one location to another? (average and examples), if they are different, what is unique about the transport of each cell? Thank you! Darren Sledjeski: within a cell things move on the actin cytoskeleton at 1-2 microns per second.
Durant High School, Florida: If we were to find a cure for cancer, wouldn't the cancer cells eventually adapt to it? Charles Edmonds: Adaptation is one of the things that cancer cells do best. So whatever measures taken to achieve a cure will absolutely have to pay attention to this possibility and guard against it. You need to remember that cancer is not just one disease but a whole spectrum of illnesses based on a wide range of mechanisms.
Bolton High School, Connecticut: What determines whether the fatty acids in the phospholipids in the cell membrane are saturated or unsaturated? Paula Flicker: There are special proteins that put fatty acids in the phospholipids. Many factors control the process. You can influence it by diet.
Hynes Charter School, Louisiana: Why does cholesterol stiffen the membrane? Joe Gindhart: It fills in the gaps between the fatty acid tails in the lipid bilayer.
West Prairie Middle School, Illinois: What is more complex a cell or a atom? Paul Sammak: Oh, a cell, of course, because they are made up of so many atoms! Another way to look at it is that we've put names on the parts of an atom and parts of a cell. The major components of atom (sub-atomic particles) are fewer than the number of components (different proteins, nucleic acids lipids and carbohydrates, all made up of atoms joined together by electronic forces in covalent and non-covalent bonds). Also the components of cells are organized into more complex, higher level structures, the organelles such as the cytoskeleton, endoplasmic reticulum nucleus, etc. A physical science perspective would be to look at the degree of order (or entropy) of the system and cells are very highly structured objects compare to a single atom. The nuclear forces that hold atoms together are exceedingly difficult to understand and as we learn how deep they are, we'll appreciate how complex atoms are.
Cheektowaga Central High School, New York: What sorts of signals does the brain use to communicate sensations, thoughts and actions?
Krishan Arora: Great question! Brain uses various signals to communicate. Every minute of every day, the cells in our brains send and receive signals that influence everything from the memories we form to the emotions we feel. Upon receiving new information, a nerve cell transmits an electrical signal, triggering the release of chemicals called neurotransmitters at special locations called synapses. These chemicals act as messengers, passing along instructions that switch nearby cells on or off.
International High School of New Orleans, Louisiana: What makes our skin brown? Alex Valm: Great question. Skin cells contain pigment granules called melanin that contribute pigment to human skin. The melanin granules are synthesized by specialized organelles in the cell called melanosomes. Melanin granules absorb light and function to protect cells in the human body from the dangerous effects of light. Different people have different skin tones based on the density of melanin granules present in their skin, determine by genetics.
Florence High school, Arizona: Hellooo! What College and Universities have the best program for biology? Which one did you attend to? Alison Gammie: There are a many schools with terrific biology programs. You can look up these rankings, but keep in mind that the ratings are typically based on the quality of the research. As a student, you should look for a program that will take your development as a scientist seriously. For example, check to see if undergraduates have access to research laboratories and if they offer mentoring programs. Good luck!!
Johnson Central High School, Kentucky: In what ways do certain bacteria help cells? Darren Sledjeski: Lots of ways! They help out immune system develop properly, prevent pathogens from colonizing us, provide essential nutrients to our cells, help us digest our food.
Johnson Central High School, Kentucky: Why is there a fixed number of neurons in the human brain? Lee Slice: There are not a fixed number of neurons in the human brain. The number changes daily. For example, when a new baby is born, their brain is growing very rapidly during the first few years. Then at a specific time, groups of neurons die as the brain matures.
Johnson Central High School, Kentucky: Do cancer cells still perform normal cell functions (ignoring the rapid and uncontrollable division)? Joe Gindhart: Yes, for the most part. The controls on cell division and migration may be disrupted, but basic enzymatic processes of cells are largely unaffected.
Gateway Senior High School, Pennsylvania: How drastic can a mutation affect a cell? Joe Gindhart: A mutation can cause cell death, which is pretty drastic!
Johnson Central High School, Kentucky: What specific precautions must you take when conducting an experiment on cells to ensure that cells do not get damaged or contaminated? Paula Flicker: Sterile tools, surfaces, and solutions are used to avoid contamination. When preparing cells for examination, e.g. in a microscope, cells are kept in appropriate solutions and treated gently to avoid damage.
Gateway Senior High School, Pennsylvania: If prokaryotes do not have mitochondria then how do they make energy? Darren Sledjeski: Actually mitochondria are related to bacteria. They both use similar metabolic pathways to produce ATP.
?Thanks again for your interest in Cell Day! We are answering questions as quickly as possible.
Durant High School, Florida: So how long where you in college before you decided that you wanted to get in your field of science? Charles Edmonds: Since I was in high school I always knew that I wanted to be a chemist. I started college as a chemical engineer but changed to pure chemistry after a year. I finished an undergraduate degree and went to graduate school in chemistry. So the story went. What, you might ask is a chemist doing studying biology. The short answer is that cells and biology it is the most interesting chemistry of all.
Effingham County Middle School, Georgia: What is your most notable discovery involving cells? Alex Valm: So far, my most notable discovery involves bacteria cells that live in the human mouth. Each person's mouth is estimated to contain about 100 different species of bacteria. Some of these bacteria are pathogens, meaning they cause diseases like dental caries and periodontal disease. But many of the bacteria in the mouth don't directly cause disease. I discovered that pathogens in the mouth are dependent upon these other cells by physically attaching to them. For more information you can read about the findings at the Proceedings of the National Academy of Sciences website here:
Johnson Central High School, Kentucky: What advances in cellular biology do you expect to see in the near future and how do you think these advances will affect the population? Alison Gammie: One interesting new frontier in cell biology is the ability to use computers to simulate how cells will behave under certain conditions. This could be useful to predict how cells will respond to drugs.
Johnson Central High School, Kentucky: How does a smaller gene pool create greater chance for mutation? Darren Sledjeski: It doesn't change the mutation rate. But, a smaller gene pool increases the chances that a specific mutation will become fixed in a population. That is the mutation will not be randomly lost.
Streetsboro High School, Ohio: Can you explain to me how ATP synthase works? Janna Wehrle: Hard question! But after many years we have a pretty good idea. The ATP synthase is inserted into a cell membrane--the plasma membrane of a bacterium or other prokaryote or the inner membrane of the mitochondrion in plants or animals. When nutrients like glucose are metabolized in the presence of oxygen, hydrogens (H+) are separated across the membranes from electrons (e-). This stores energy like a battery. The ATP synthase membrane section ('Fo') creates a path for H+ to move thru the membrane and delivers them to one of the three major parts the huge F1 enzyme. The changes in the F1 enzyme structure caused by the new H+ promotes the formation of ATP from ADP and phosphate. F1 has three ATP synthesis sites and they are each used in term--a sort of Wankel engine.
Gateway Senior High School, Pennsylvania: Do cells communicate with each other? If they do how? Lee Slice: Yes, cells communicate with each other and with their environment. Cells have receptors on their surface that when the correct molecule binds to it, it starts a signaling pathway within that cell. Also cells can release molecules that can bind to receptors on neighboring cells and start that cell's signaling pathway. This is called signal transduction.
School of the Osage High School, Missouri: What do you do in your free time when you are not working? Jessica Faupel-Badger: Thank you for this question! It's important to have work-life balance. I'm learning to knit but have been working on the same hat for over two months.
Millsboro Middle School, Delaware: Hi, we are from Millsboro, Delaware and wondering about something we read recently in a magazine. Cells have memories and can remember damage to them. Is that true? Thank you. Darren Sledjeski: One process that allows cells to have non-genetic memory (that is not encoded in the DNA base pairs) is called epigenetic. These are modifications that happen to the DNA backbone that control when some genes are turned on or off. Some of these changes can be passed on to daughter cells. This is an active and exciting area of scientific research.
Gateway Senior High School, Pennsylvania: Are there any multicellular prokaryotic organisms? Alex Valm: Scientists generally don't consider prokaryotes to be multicellular, but recent evidence suggests that most prokaryotes live in close context with other cells. Prokaryotes can form complex multicellular structures called biofilms. Biofilms are very similar to eukaryotic tissues and organs because they contain different cell types that work together to perform certain functions. As well, biofilms have specific structures that correlate with their function, just like an organ in a plant or an animal. The main difference between biofilms and eukaryotic tissues is that the prokaryotic cells in biofilms are genetically distinct: they are not related to each other whereas the different cells in a eukaryotic tissue all have the same DNA.
Glenview Middle School, Illinois: What effect does cancer have on the brain? Lee Slice: Cancer cells in the brain do damage by growing colonies of cancer cells that crowd out neurons and normal support cells in the brain. This results in disruption of the normal brain functions such as neurons firing and can cause neurons to die by blocking oxygen to the neurons.
Gateway Senior High School, Pennsylvania: What is the most common organelle found in a cell? Stefan Maas: This depends on the type of cell you are looking at. For example, muscle cells, whose main job is to produce energy, the mitochondria are the most numerous. For tissues specialized on secreting hormones or other molecules, such as liver or pancreas, the endoplasmic reticulum is the predominant organelle.
Francis Lewis High School, New York: What are some of the most common genetic mutations that occurred within cells within a plant or a person's lifetime? Krishan Arora: Great question! Most common genetic mutations that can occur are deletion, insertion and microsatellites. A microsatellite is a tract of repetitive DNA in which certain DNA motifs (ranging in length from 2–5 base pairs) are repeated, typically 5-50 times. Microsatellites occur at thousands of locations in the human genome and they can cause high mutation rate and high diversity in the population.
Cheektowaga Central High School, New York: What things are being tested for cancer research? Charles Edmonds: It is important to remember that cancer is not just one disease but a long list with many different cells and cell processes going out of control. So the list is very long. One of the most productive approaches to all these different problems is the discovery and development drugs which slow or prevent the rapid growth of cells in cancer.
Sinaloa Middle School, California: Have you ever come across a zombie cell in your years of research? If so what was your reaction? Joe Gindhart: Not that I know of, but I will be careful to avoid them.
Sinaloa Middle School, California: Where do cells go when they die? Stefan Maas: They don't need to go anywhere; the immune cells that clean up the leftovers of the dead cells will find them. Some of the molecular components are thus recycled in the organism.
New Tech High @ Coppell, Texas: What does THC (Tetrahydrocannabinol) do to the cell? Lee Slice: THC binds to cannabinoid receptors on neurons, which generates a signaling pathway within that neuron, which effects the behavior of that neuron.
Mountlake Terrace HS, Washington: When you cook red muscle cells, why do they turn grey? Janna Wehrle: Fresh meat is red or pink because some of the hemoglobin pigment protein in the remaining blood is still carrying oxygen in a special shape of the protein. When the meat is heated, the hemoglobin protein is 'denatured'--it loses its special shape, and so it's red color.
Holmes Middle School, Colorado: Why is there no nucleus in a bacterial cell? Darren Sledjeski: bacteria do have a nuclear like structure called a nucleoid. It is not as structured or membrane bound like a eukaryotic nucleus. But it can provide similar organization functions.
Woods Charter School, North Carolina: How would x-ray crystallography help you learn more about a cell? Paula Flicker: Using X-ray crystallography, one can see the detailed shape of macromolecules to atomic resolution. The shape is important to the function. Just as a key must be the right shape to fit a lock, parts of the cell must be the right shape to work together. X-ray crystallography can be used to look at the shape of a molecule or complex in different states such as bound to an inhibitor or in an active state. Knowing the detailed structures of proteins and nucleic acids helps us understand how they work and how to design drugs to halt their function.
Johnson Central High School, Kentucky: What do cells eat? Jessica Faupel-Badger: Great question! There are different mechanisms by which a cell can either passively (no energy required) or actively (energy required) sample their environment. Examples of these processes include endocytosis (actively bringing materials in from the outside environment) and pinocytosis (bringing in fluid from the outside environment). These materials can then be directed to the appropriate intracellular space or compartment.
Imagine International Academy of North Texas, Texas: Are you experiencing a really high volume? Students in my classroom are very eager to see their Qs answered:)
Joe Gindhart: Yes, we are answering the questions as fast as we can. I apologize for the delay. Thank you for your interest in Cell Day; I will post some quiz questions to the chat, and there are lots of other useful Cell Day facts there, too.
Gateway Senior High School, Pennsylvania: How do they target cancer cells when they are doing radiation and chemotherapy? Lee Slice: Generally radiation and chemotherapy is targeting cells that are rapidly dividing such as cancer cells. There are more specific chemotherapies that connect toxic molecular to antibodies that bind to targets on cancer cells.
Effingham County Middle School, Georgia: Can cells have symbiotic relationships with other organisms like bacteria? Alex Valm: Many eukaryotic and prokaryotic organisms have symbiotic relationships with bacteria. The human microbiome project has revealed that there are hundreds or perhaps thousands of species of bacteria the live on and within the human body. Some of these bacteria are known to be pathogens (they cause disease) and some are known to be beneficial (E. coli and other bacteria in the human gut synthesize vitamin K). Most of the bacteria in the human body are considered commensal, meaning they neither benefit nor cause harm to the human body. But recent evidence suggests that the complex community of micro organisms in the human body plays important roles in human health and diseases including immune system function and allergies. For more info check out the human microbiome project website:
Mountlake Terrace HS, Washington: Even though viruses aren't technically alive, are they somehow related to cells? If so, how did they evolve to be different? Darren Sledjeski: Some virologists would argue that viruses are alive. But I wouldn't. They are parasites are that are absolutely dependent on the host cell for the ability to metabolize and reproduce. They evolve fast because they tend to replicate faster and in an error prone way. The evolution of viruses is a fascinating field of study.
Johnson Central High School, Kentucky: Are cells squishy?? Paula Flicker: Some cells or parts of cells are squishy. How stiff or squishy an individual cell is can change over time as a cell moves and/or contacts other cells.
West Prairie Middle School, Illinois: How old do you have to be to retired if you are a scientist? Stefan Maas: There is no general rule; it will depend for example much on in which country you live and within any given country, in what kind of job you are working as a scientist. For example, in many countries university researchers pretty much have to retire when then turn 65 years old. In the US, there is no such obligatory retirement age; many US researchers are active in their job as long as they like to, or as long as they are able to secure funding for their laboratories.
Clarkstown High School North, New York: Biobeat mentioned that "By studying the mechanisms that lead to zombie cells, scientists can find clues for how to prevent their formation." Have scientists found clues? If so, what are they? Joe Gindhart: Mutations that call 'zombie cells' are often involved in the regulation of cell division. For example, there is a checkpoint during metaphase that prevents anaphase from occurring before all chromosomes are aligned on the mitotic spindle. Disruption of this checkpoint control can cause aneuploidy and perhaps even 'zombie cells'.
International High School of New Orleans, Louisiana: Has anyone been cured of HIV? Lee Slice: Yes, AIDS is caused by the HIV virus. Anti-AIDS drugs such as protease inhibitors and inhibitors to HIV reverse transcriptases have been very effective at blocking replication of the HIV virus in the body. In some cases, it has worked so well that some infected people can no longer have any HIV virus detected in their blood and generally you are considered cured if you have no detectable HIV viruses for 5 years.
Johnson Central High School, Kentucky: What are the specific differences between the bacteria that cause diseases and the ones that don't? Alex Valm: bacteria that cause disease are called pathogens. Pathogenic bacteria differ from nonpathogenic because they have specific molecules, called virulence factors, that make them able to cause disease. These molecules either directly cause damage to eukaryotic cells or they elicit an immune response from animals. The human microbiome project has revealed that there are hundreds or thousands of species of bacteria that live on and in the human body. The vast majority of these bacteria species are considered commensal because they do not directly cause disease. To learn more about the human microbiome project, check out the website:
Johnson Central High School, Kentucky: PLEASE ANSWER, I REALLY NEED TO KNOW!...What components of cells make fruits different colors? Joe Gindhart: Pigments.
Sinaloa Middle School, California: How come your body stays together with cells? Why doesn't it just fall apart? What's keeping your cells together? Paula Flicker: Cells are kept together by their contacts with each other and their contacts with the space between cells, the extracellular matrix. The extracellular matrix is complex mixture of fibers and proteins such as collagen.
Van Antwerp Middle School, New York: How does an organism as a whole die? Krishan Arora: Great question! The organism as a whole dies when homeostatic balance is disturbed and cells are not able to perform essential functions. Whereas, some cells that are grown in culture media are immortal and can keep dividing. For example, cancer cells are immortal.
Mountlake Terrace HS, Washington: How do you think plants and animals would get the energy they need if mitochondria didn't achieve an endosymbiotic relationship with modern plant and animal cells? Darren Sledjeski: Good question. Someone has been reading their HS Bio textbook. I think that without mitochondria large multicellular organisms would not have evolved. They need lots of the specialized energy to survive. Life on Earth would be dominated solely by small single cell organisms.
Sinaloa Middle School, California: What is the heart cells main job? Paula Flicker: The main job of heart cells is to contract regularly without stopping.
Pemberton Township High School, New Jersey: Good morning! Up to my high school career I've always had an obsession with law and becoming an attorney. After biology and genetics entered my life, my teacher told me I could en corporate both through a career as a pharmaceutical attorney. What degree of education would I need and what would I be doing?
Joe Gindhart: You would likely need an advanced degree (M.S. or Ph.D.) in a life science, as well as a law degree.
Check your cell IQ! The type of cell division that creates sperm and egg cells is called mitosis.
The correct answer is: B. False.
The type of cell division that creates sperm and egg cells is called meiosis, not mitosis.
Check your cell IQ! The cells shown here in red have many important jobs. They store and release energy, protect organs and nerve tissues, insulate us from the cold and help us absorb important vitamins. They are:
The correct answer is: D.Fat Cells.
Fat cells are vitally important to the body's health.
Upper Dauphin Area Middle School , Pennsylvania: What is CRISPR? Stefan Maas: Naturally, CRISPR is a bacterial defense/immune mechanism used to defend them against foreign DNA, such as that from bacteriophages and plasmids. However, recently the insights into the bacterial CRISPR biology has been exploited to develop a highly powerful gene editing tool for any kind of cells. Researchers are able to use this tool to make one or many specific changes within the genomic DNA of an organism.
Mountlake Terrace HS, Washington: Are nanobacteria alive? How did you come to this conclusion? Darren Sledjeski: The existence of nanobacteria remains controversial. Some scientists are convinced they are living reproducing organisms other think they are artifacts of the experimental conditions. The existence of nanobacteria is hard to explain with our current understanding of cells and cellular processes so we would need much more evidence to be confident that they are alive.
Sinaloa Middle School, California: What's the difference between a squid axon and a human axon? Jessica Faupel-Badger: The squid giant axon is often mentioned as one of the largest cells. This axon runs the almost the length of the squid and can be up to a 1mm in diameter. This is much larger than the human axon that is a few micrometers in diameter. The longest axon in a human is from the sciatic nerve, which runs from the base of the spine to the big toe.
Sinaloa Middle School, California: What are the biggest and smallest cells? Joe Gindhart: bacteria are pretty small, and I would argue that a nerve cell in a giraffe or whale would be the largest.
Glenview Middle School, Illinois: How does a genetic disease start in your blood line if you have never had it before? Lee Slice: This is a hard question to answer in that a genetic disease is one that is inherited from your parents in your chromosomes. But when or if disease emerges depends on a lot of factors including environment. An example would be a mutation in DNA repair, say a pair of twins had the same mutation but one smoked and the other twin did not. Chances are the one that smoked would have more mutations in their DNA that could result in cancer and thus would likely have cancer earlier in life compared to the other twin that was a nonsmoker.
Mountlake Terrace HS, Washington: How do you think the endosymbiotic relationship between mitochondria and the cell originally through evolutionary processes? Kris Willis: Hi Mountlake Terrace! A very thought-provoking question. We don't know for sure just how this happened, so I can only hypothesize. Cells have a process called autophagy, through which they can engulf molecules or other cells; we think that somehow the ancestor mitochondria was engulfed by the ancestor of all eukaryotic cells. This gave the ancestor eukaryote an advantage that allowed it to grow and divide more efficiently. Over time, many of the mitochondria's genes were transferred to the nucleus, which made it easier for the mitochondria to grow and divide inside the 'host' eukaryote, and so a symbiotic relationship was formed.
Mountlake Terrace HS, Washington: How do you see the cells as part of your life rather than an abstract concept independent of everything else? Darren Sledjeski: Cells are not an abstract concept they are a physical presence that is the basis for life on Earth. Cells are the general organizing principal for how life has evolved and led to us.
Johnson Central High School, Kentucky: Are there any new microscopes that are being developed for more in depth imaging of cells? Alex Valm: This is one of my favorite topics, thanks for the question! Developing microscopes is a very active area of research. One of the hottest areas is developing microscopes that can resolve objects that are smaller than can be resolved by current light microscopes. The 2014 Nobel Prize in Chemistry went to three researchers who are developing these 'superresolution' microscopes. One of these techniques called PALM for photo-activated light microscopy makes use of the fact that fluorescent molecules blink. Specific structures within cells are labeled with these fluorescent molecules, then their blinking behavior is imaged. Then, some sophisticated math and statistics are used to determine where the individual molecules are in the cell down to 10-20 nm accuracy. Development of new technologies for studying cells is an active area of research and requires scientists with many different skills to work together. For more information on the 2014 Nobel Prize in Chemistry check out their website:
Sinaloa Middle School, California: is the nucleolus more important than the nucleus? Darren Sledjeski: They are both essential for the function of eukaryotic cells. You can't survive with out both!
Mountlake Terrace HS, Washington: Why would a more archaic scientist think to discover organelle with no previous knowledge? Paula Flicker: Discovery science, sometimes one finds unexpected things just by looking. Experiments often give unexpected answers and usually generate new questions.
Johnson Central High School, Kentucky: What do you consider to be the biggest ethical issue in genetics?
Paul Sammak: The ability to edit the genome of living creatures, including humans is one of the most challenging issues. There are therapeutic uses for gene therapy that could correct genetic errors in the body that causes disease. The ethical issues include the safety and the health promise of treatment. Genetic changes to body cells would not be passed on to offspring. However, genetic changes that could be inherited require a much higher level of ethical evaluation and reflection on what is beneficial, what is right and what do we as a society support. Newer methods for modifying the genome with editing enzymes such as the CRISPR/Cas9 system demand careful thought and firm rules about is allowed. Standards and regulations for these experiments are being prepared. There is agreement that changes in humans that could be inherited would not be prudent.
Sinaloa Middle School, California: How many groups of cells are there in the body Darren Sledjeski: Scientists estimate there are about 200 cell types and a few trillion cells in the human body. That does not include bacteria, fungi, viruses and mites that live in and on our bodies. These microbes outnumber our own cells several times over. Many of them are important for keeping us healthy. To learn more, check out the Human Microbiome Project at
School of the Osage High School, Missouri: What do drugs do to your cells? Janna Wehrle: Any drug has to interact with one or more cells in the body. Many drug 'targets' are proteins. DNA can also be a drug target. When the drug binds to a protein or DNA, it can speed up, slow down, or prevent the action that the protein is supposed to carry out. This may kill the cell the target is in, or make it behave strangely. If the target is a cancer cell, drugs are designed to promote cell death. If the target is a blood vessel lining cell, the drug may be designed to help it relax. A major challenge in drug design and discovery is to avoid unintended interactions that can cause side effects.
Glenview Middle School, Illinois: If there has never been any previous genetic diseases of the sort, how does one start? Charles Edmonds: Genetic diseases arise from changes in the genes of the cell. These mutation changes can occur spontaneously during replication of the DNA of cells or as the result of physical or chemical agents from outside the cells. These changes can result in prompt death of the cells or they may preserved through successive generations of DNA in dividing cells. These mutation changes can show in the tissues of the initial organism, showing up as the rapidly dividing cells of a cancer. Or they can also be passed in successive generations during reproduction showing up as disadvantageous heritable traits in subsequent generations.
Johnson Central High School, Kentucky: What are the challenges faced with stem cell research? Jessica Faupel-Badger: The major challenges with stem cell research are, from a biological point of view, to understand how to consistently stimulate undifferentiated cells to become differentiated cells of a specific type, to regulate proliferation of the differentiated cells, and to have these new cells survive in the location of the body where they are needed. NIH has a great resource if you would like to read more about stem cells - http://stemcells.nih.gov/info/Pages/Default.aspx
Mountlake Terrace HS, Washington: When Does a cell decide to undergo cell lysis, and what is responsible for sending that message? Stefan Maas: Usually, a cell will only enter the process of cell death if it has suffered damage beyond repair. Even then, most cells will die without undergoing cell lysis, since the sudden release of the cell contents can lead to inflammation and autoimmune responses.
Sinaloa Middle School, California: What is the difference between a prokaryotic and a eukaryotic cells? Jessica Faupel-Badger: Eukaryotic cells contain a nucleus and other organelles and often have specialized functions. Prokaryotic cells are less complex, without a nucleus and commonly exist as single cells. Prokaryotic cells are generally smaller (1 - 10 microns) than eukaryotic cells (10 -100 microns).
chart for comparison [PDF]
Sinaloa Middle School, California: How did living things come to be when they had no parents and nothing before them? Darren Sledjeski: That is a question that has intrigued scientists for a long time. There are a number of different theories but we are still not sure. A current theory is called the RNA World Hypothesis. It is thought that RNA molecules evolved first to be self replicating and have some enzymatic activities. Proteins and cell structures evolved later. But, we still do not have a complete answer to the question. Want a Nobel Prize? Become a scientist and answer this for us!
Sinaloa Middle School, California: How big is a cell? Don't just say really small? Joe Gindhart: Cells range in size from about one micron (bacteria) to meters in length (nerve cells).
St Thomas the Apostle School, New York: Are the amount of cells in children different from adults? Do we have all the cells we need in a lifetime? Lee Slice: In our body, cells are constantly dying and being replaced by new cells, mostly by stem cells that continuously divide and produce new cells.
Thank you again for your support of Cell Day. We are answering your questions as fast as we can.
Clarkstown High School North, New York: How quickly can bacteria evolve to create new strains, and are these strains that evolve always stronger than before, or can the process of changing its DNA cause it to weaken? Alex Valm: Although we don't have a very good definition of what a bacterial strain is, we do know that bacteria can evolve relatively fast compared to other organisms. Bacteria evolve when there is a specific pressure in their environment: for example, when exposed to antibiotics, bacterial populations often evolve resistance. Antibiotic resistance genes very often make bacteria less fit for their environment when there is no antibiotic present. Therefore they can be considered weakened. Also, when there is no antibiotic present, bacteria evolve and lose their resistance, so this could be considered weakened as well.
Sinaloa Middle School, California: What is the most important cell in the body? Kris Willis: Hi Sinaloa Middle School! That's a good question. All the cells in the body are important; they all have their own purpose. For example, the cells in your lungs help you breathe, the muscle cells in your heart circulate blood, your skin cells protect you from the environment around us. We need all these things equally.
Sinaloa Middle School, California: I know that cells reproduce and die everyday, but what would happen if too many of someone's cells died and not enough were reproduced? Stefan Maas: If this would happen within the blood, that individual would soon die since there would not be enough red blood cells to transport oxygen in and CO2 out. While the half life of other cell types is longer than that of blood cells, in many cases such a situation would be detrimental.
Mountlake Terrace HS, Washington: Would it be possible to bioengineer a virus to be a living organism? Darren Sledjeski: Interesting question. Theoretically yes. But at some point it would become a cell and no longer a virus. In fact some viruses exists that are at the border between what we consider a virus and what we consider a cell. Google 'Mimivirus' for more cool information.
Mountlake Terrace HS, Washington: Do insect cells function in a similar way to mammal cells? Paula Flicker: Yes. In fact, in some cases insects are used as model organisms to gain insight into how mammalian cells work.
Clarkstown High School North, New York: Biobeat stated that "Some bacteria produce light in certain conditions." What are these conditions? Does it only occur in water? In certain temperatures? Janna Wehrle: The particular bacteria in that story were marine bacteria, but the ability to signal thru bioluminescence is much broader among the biological world. (Think fireflies.) The reactions that produce light do take place in water, because they occur inside of cells. And, yes, the light-forming reactions are temperature-sensitive--either too cold or too hot will interfere, for different reasons.
Mountlake Terrace HS, Washington: Do mushroom cells function differently because they are decomposers? Darren Sledjeski: Nope. They function the same. But, they get their energy by breaking down dead organisms rather than from the Sun (plants) or by ingesting and digesting food. You can think of them as doing their digestion outside of them rather than inside like we do.
Clarkstown High School North, New York: Are circadian rhythms present in single cells, or is that something that is only present in an organism as a whole? Stefan Maas: No, circadian rhythms have also been found in single cell organisms, such as cyanobacteria and fungi.
Sinaloa Middle School, California: Can cells be considered smart? Paula Flicker: Cells cannot be considered smart in that they do not 'think'. Nonetheless, cells are impressive machines that perform complex functions and interactions with their surroundings and respond to cues.
Sinaloa Middle School, California: Why did you want to become a cell scientist? Paul Sammak: I was always curious. I always loved to build things. Before I was even in school I asked lots of questions about how things worked. When I was in middle school, I had a great feeling of satisfaction when I understood how the natural world worked. My first questions were more about engineering. I loved airplanes and how airflow made planes fly. In college, I decided to study physics so I could understand how fluids flowed and changed shape, and I loved looking through the microscope to watch flowing water and chemical formation. I liked microscopes and light so much that I thought I would study the most interesting thing I could see in the microscope. So changed my field of study from physics to cell biology. My Ph.D. was in biophysics and I developed new microscope technologies to understand cell movement and structure. Since then, I have worked to make new technologies that use light, images and microscopes to understand how cells move grow and change.
Johnson Central High School, Kentucky: Has technology for cell research advanced as quickly in the past years as common technology like phones? Charles Edmonds: Common technology and 'uncommon' advanced technology all comes from the same pool of innovation. So all the high speed changes we see at home are showing up as wonderful technical innovations in cell biology studies. The changes which I am most familiar with are occurring in the field of structural biology which looks at the processes within the cell at the molecular level. It is becoming possible to look at the molecular machines which drive the processes of life and understand how they work in health and in disease. It is good. It gets me out of bed in the morning.
Mountlake Terrace HS, Washington: Does the radiation from tanning beds kill or affect our skin cells? Alex Valm: The light radiation from tanning beds, especially the very high energy UV radiation that causes the skin to tan is known to cause damage to skin cells. Particularly, UV radiation causes damage to DNA called double strand breakage. The energy is absorbed by the skin cells' DNA and this causes it to break. The cell then uses specific enzymes to repair the DNA, but double strand breaks are very difficult to accurately repair--this usually leads to mutations in the cell. Many of these mutations cause the skin cells to die, so the radiation from tanning beds can definitely kill skin cells. When skin cells die, the body elicits an immune response called inflammation: this is what we call a sunburn. What's more dangerous though, is that sometimes the DNA mutations caused by UV radiation lead to skin cancer. This happens when certain genes, called tumor suppressors are mutated and become inactivated or when tumor promoters become activated.
Sinaloa Middle School, California: Can you make dinosaurs with DNA? Joe Gindhart: In the movies, but not in real life.
Mountlake Terrace HS, Washington: When you want to test something unique, how do you go about creating a procedure? Jessica Faupel-Badger: This is a great question! And, I can tell you are thinking like a scientist. When a scientist is looking to test a new question, we start by reading a lot! We read the research publications of other scientists to see what we can learn from how others may have approached a similar problem in a related field. We then use this prior knowledge as a starting point for developing the new protocol. It is absolutely necessary to keep a detailed record (lab notebook) of the different conditions you have tried and the outcomes. This enables you to learn from your results and then communicate your findings to others so future experiments can build on your work.
Lake Highland Prep, Florida: How does a person become colorblind? Lee Slice: The retina in your eye contains two types of photoreceptors, rods and cones. Rods are the most numerous photoreceptor cells but they are not sensitive to color. A person is color blind when they are missing one or more of the three types of cones. Males are more likely to have color blindness because they only have one X chromosome, which is were the genes are located.
International High School of New Orleans, Louisiana: What is a stem cell? Paula Flicker: Stem cells can regenerate themselves and can produce offspring that are different (differentiate).
International High School of New Orleans, Louisiana: What are iPS cells? Darren Sledjeski: iPS stands for induced pluripotent stem cells. These are cells that have been changed (induced) to de-differentiate. They can then be used to form other cell types. They are not the same as Stem cells but still have many potential uses.
Hi everyone. We will receive questions for about 15 more minutes, and answer as many as we can. We appreciate your patience.
Sinaloa Middle School, California: What are your jobs? What do you do every day? Charles Edmonds: I started my career as a chemist. I worked as a research scientist studying the molecular processes involved in the damage and repair of DNA caused by the energy production technology such as petroleum base and nuclear power generation. I am now working in an office as a science administrator assisting other scientists who are still working in the laboratories to improve the diagnosis, treatment and prevention of disease.
St. Charles Borromeo School, New Mexico: Why does human skin have an outer layer of dead cells? Stefan Maas: That's a good question. On one hand, the layer of dead cells is just a result of the life cycle of skin cells, however, this layer of the skin does have important functions. It is the first protective layer of the body and protects against infection and dehydration. It also represents an important location for the skin microbiome.
Durant High School, Florida: What originally interested you in cells? Krishan Arora: Interesting question! During high school and college years, I always wondered how cells look like, what makes them different cell types. How do they function and talk to each other? Why do these cells get sick? What makes them to change from normal to diseased state? To be able to answer some of these questions, I took science courses - biology, biochemistry, chemistry and physics during my college years. I underwent training for several years in research laboratories.
International High School of New Orleans, Louisiana: Does anyone in this room know this question? Can ATP add another phosphate group? Joe Gindhart: I don't think so. I can't think of an example of a molecule with four phosphates in a row; that molecule would be very unstable.
International High School of New Orleans, Louisiana: What effect can weed have on a person? Lee Slice: Weed has cannabinoids, which bind to and activate cannabinoid receptors in the brain. It can increase your appetite, stop the feeling of being sick to your stomach, decrease pain, and lower higher reasoning and logic.
Mountlake Terrace HS, Washington: If organelles had a consciousness would they complain all day? Charles Edmonds: Yes, I suppose that they would. Life is about change even at the mitochondrial level. Change is always difficult.
International High School of New Orleans, Louisiana: What happens to ATP after it uses all of the energy? Paula Flicker: The ATP is regenerated by adding a phosphate to ADP. There are proteins designed to add the phosphate to ADP.
East Syracuse Minoa CHS, New York: I was wondering what exactly is a biochemist? and what is a normal day for you in your line of work? thank you for your time. Jessica Faupel-Badger: Biochemistry is focused on understanding the chemical processes related to living organisms. In a cellular context, a biochemist may be interested in understanding the different signaling pathways that stimulate a cell to divide, move, or survive. These processes are mediated by a vast array of chemical reactions between different molecules as the signal is transmitted throughout the cell. There are jobs for biochemists at all educational levels and in different settings. Biochemistry is a field you can major in when you are in college, or at least take a class in to see if this would be a good fit for your interests.
Dudley Middle School, Massachusetts: Could you combine different plant cells to make a hybrid plant? Joe Gindhart: Yes! For example, growers graft the fruit-producing part of a plant onto the roots of a different plant; this way, you can get the best properties of both plants.
East Syracuse Minoa CHS, New York: Would it be possible to take the genes from one species, and give those traits to another species? If not, why? Alex Valm: The process of transferring a gene from one organism into another is called genetic engineering and is absolutely possible. Biologists routinely transfer fluorescent proteins from jellyfish and other marine organisms into laboratory cells in order to study particular cellular processes involved in health and disease. As well, genes from bacteria and insects have been transferred to plants to make them resistant to insects and pathogens. Some genes cannot be expressed properly when transferred from one organism to another because they don't have the proper cellular machinery so it's not always possible. New technology called CRISPR allows the insertion of genes in specific locations within a cell's chromosomes and holds tremendous promise for treating genetic disorders in humans.
East Syracuse Minoa CHS, New York: I was wondering how people are born with two different eye colors and how rare that is? Janna Wehrle: There are a couple of ways an individual's eyes can begin or take on different colors. Sometimes it's a result of some or another very rare genetic conditions. It can also be a change in the level of the dark protein melanin that's mixed in with a color pigment. This can change over time, or after eye injury. Perhaps you've seen brown spots on the skin that change, often with age? This can happen to melanin in the eye as well.
Dudley Middle School, Massachusetts: Can you make an artificial cell? Lee Slice: No, at present you need a cell to make a cell. Specifically, the three things that you need from a cell in order to make a cell is a mitochondria, the cell nucleus, and the membrane system. These three things cannot be made from elemental parts but must come from a cell.
Mountlake Terrace HS, Washington: Do plant cells control defense mechanisms? Like poisons, idioblasts, and chemical signals? Paul Sammak: Plants can respond to stress in their environment by producing bioactive molecules. For example toxins that defend against insects, bacteria or fungal infections. Some of the molecules that are produced to defend against invaders make the plant not healthy for us to eat. However, plants that are under environmental stress such as drought can produce molecules that protect the host plant and when we eat some plants that are stressed, we benefit from those plant-produced defense molecules. There are many scientists studying phytotoxins and nutrients and the story about how plants adjust to their conditions will be very exciting.
Pennfield School, Rhode Island: What are your favorite organelles? Charles Edmonds: The nucleus is the queen of organelles. The nucleus is where all the important things happen, all the decisions are made and where these appear in succeeding generations of cells, organisms and everything.
Dudley Middle School, Massachusetts: How can one cell tell whether another cell is infected. For example a cancerous cell or Dna infected cell. Lee Slice: The infected cell sends out a chemical signal that other cells recognize and then act upon. T-cells and macrophages destroy virus infected cells in your body as part of your immune response.
Silva Health Magnet High School, Texas: Could bacteria be specially modified to create oxygen in other planets? Alex Valm: Sure! Cyanobacteria are bacteria in aquatic environments that use sunlight to convert water and carbon dioxide into carbohydrates and oxygen, just as a plant does. It is hypothesized that bacteria like these initially contributed oxygen to the earth's atmosphere. In order to create an oxygen rich atmosphere on a planet that doesn't have oxygen, but does have carbon dioxide, the bacteria would need to pump out a lot of oxygen. So you'd probably want to modify a cyanobacteria organism to increase it's oxygen output or perhaps its growth rate. This is all wild speculation and would take a lot of resources, but from a cellular/molecular standpoint it's possible!
International High School of New Orleans, Louisiana: What do you like about your job? Kris Willis: Hello International High School of New Orleans! There are lots of things I like about my job. My favorite thing is learning new and exciting things about how cells work. It's really neat to discover things that no other person has ever known before! But I also really like talking to other people about science, so I'm having a lot of fun today. ;)
Johnson Central High School, Kentucky: If cells are equipped to deal with toxins, how is it that we are poisoned? Is it from being overwhelmed by the amount or does it vary with cell type and toxin? Paul Sammak: There are lots of mechanisms that cells use to excrete toxins or chemically detoxify poisons. However, the first line of defense is a barrier that protects against exposure. For an organism, that would be the skin. For a cell, that would be the membrane that is impermeant to water soluble poisons. The most important variable on whether a toxin is dangerous is dosage. If exposure is high enough, a toxin will overwhelm the defenses of the body or of exposed cells. This holds true for all toxins. The dose response for toxicity depends on the particular molecule or drug, but also on the delivery rate and total exposure of the molecule.
PERU HIGH SCHOOL, Indiana: When a spinal cord snaps or is cut will we ever get to the point where we could fix it or transplant a spinal cord or something like it to bring the person or thing back? Jessica Faupel-Badger: This is a great question and one that many people are working on. The spinal cord connects the information from the brain to the rest of the body. The requires many different cell types communicating with each other. So, it is not just replacing the physical structure but also reconnecting the entire network.
Mountlake Terrace HS, Washington: What is the biggest problem that you have encountered while working with cells? Charles Edmonds: A group of colleagues and myself were interested in the molecular events which occur in a cell during DNA damage arising from the impact of a single alpha-particle from a decomposing molecule of radon gas. The members of this group include physicists, chemists and engineers. The problems occurred on a daily basis and some solutions came easy and some are still being cracked. It was very interesting.
PERU HIGH SCHOOL, Indiana: My eyes are blue, but they change color depending on my mood. Light blue to dark ocean blue. Is there a certain reason why this happens? Janna Wehrle: The appearance of blue, green, and hazel eyes results not from a blue pigment, but from the scattering of light in the 'stroma' of the eye, similar to like phenomenon that causes blueness of the sky. Because of this, blue eye color is especially dependent on the lighting conditions, especially for lighter-colored blue eyes.
Potomac Senior High School, Virginia: What are the challenges of being a microbiologist? Kris Willis: Hi Potomac Senior High School! Well, every job has its challenges. I guess the hardest part of being a microbiologist is that you're always dealing with the unknown - you're asking questions for which nobody has the answers. That can be frustrating. But it's also the best part, too. :)
Mountlake Terrace HS, Washington: How would endosymbiosis have first naturally occurred to have created the first iteration of something resembling eukaryotic cells? (rather than simple prokaryotic cells) Alex Valm: Thanks for this great question. It is hypothesized that one of the key evolutionary events that lead to the formation of eukaryotic cells was an endosymbiotic event between two bacteria in which a proteobacteria was engulfed by another bacteria. Bacteria engulf other bacteria in order to digest them for nutrition. With this endosymbiont, the engulfed bacteria was protected from being digested. Over time, the proteobacterium endosymbiont reduced its genome size and became dependent upon the host cell for many genes. This is considered the transition from endsoymbiont to organelle.
Effingham County Middle School, Georgia: Can we bring back extinct animals by manipulating cell DNA? Lee Slice: Yes, in fact there are efforts to harvest the bone marrow cells from wooly mammoths that lived 12,000 years ago but are now extinct. They find well preserved mammoths in the permafrost in the arctic region. They plan on removing the nucleus and implanting it into an elephant embryo egg and implant it into a mother elephant for gestation. Hopefully, it will result in a little wooly mammoth.
Sinaloa Middle School, California: Is it possible to to make a mechanic kidney or heart if you are hurt in battle? Would you still function properly even if it doesn't have cells? Paul Sammak: If you are hurt in battle, time is the most important variable for how long you live after a non-fatal injury. If your kidneys are injured you can survive without removing toxins that build up in your blood for a while. Patients with insufficient kidney function can undergo mechanical dialysis (filtering) with machines that remove toxins from the blood. They are treated every few days. If your heart is damaged, oxygen in your red blood cells is not delivered to your brain and other vital organs and you have only a few seconds to survive before you would become unconscious. If you can maintain circulation with a pump so that your brain has enough oxygen, you can stay alive, giving your heart a chance to be repaired or replaced. Mechanical blood pumps can keep someone alive for many days. The long term problem with mechanical pumps and filters is that they don't match the body perfectly and there are problems with infection, clogging or clumping that cause people to get sick. The reason scientists are working on cell-based tissue repair is that these solutions are better matched to the body and can be continually repaired throughout the life of the patient.
East Syracuse Minoa CHS, New York: I was wondering what does a geneticist do and how much do they get paid annually? Kris Willis: Geneticists do a lot of different things. Some of us talk to people about their genetic makeup (genetic counselors); others use model systems like fruit flies or worms to study how different genes function. Annual salary depends a lot on exactly what the job is and on your career level, like everything else.
East Syracuse Minoa CHS, New York: What causes cellular mutation and what is the most important cell in a human? Kris Willis: Many different things can cause mutations. Sometimes the machinery that makes new copies of our DNA makes a mistake; other times, ultraviolet light or chemicals can damage the DNA. These kinds of errors and damage are happening all the time! Fortunately our cells have a really sophisticated system for detecting and repairing errors and damage, though; in fact, this year's Nobel Prize in Chemistry went to three scientists who study DNA repair. A mutation happens when DNA gets damaged, but isn't repaired.
As for your second questions, all the cells in the body are important; they all have their own purpose. For example, the cells in your lungs help you breathe, the muscle cells in your heart circulate blood, your skin cells protect you from the environment around us. We need all these things equally.
Pennfield School, Rhode Island: How ribosomes produce proteins and why cells need to contain thousands of ribosomesKris Willis: Hello Pennfield School! Ribosomes work together with transfer RNA (tRNA) to produce proteins. The tRNA kind of works as an adaptor molecule; one end of a tRNA molecule recognizes the messenger RNA (mRNA), while the other end is linked to one of twenty amino acids, which are the building blocks of proteins. The ribosome disconnects the amino acid from the tRNA and attaches it to the next amino acid in the protein chain coded by the mRNA. Cells need thousands of ribosomes because one cell needs to produce many, many thousands of proteins.
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