In our miniseries on genetics, we've introduced the genome and how variants in DNA affect us. We've also discussed how people inherit genetic information and the way genes are expressed, as well as common tools researchers use to study DNA. We hope you've paid close attention because it's time to test your knowledge of genetics! Take our quiz below, and let us know how many questions you answered correctly.

You may wonder how scientists study something as tiny as DNA. Over the past decades, researchers have developed a wide range of tools and techniques to help them unlock the secrets of human genomes and those of other organisms. Two key examples are DNA sequencing and gene editing.

DNA Sequencing

DNA sequencing, sometimes called gene or genome sequencing, enables researchers to "read" the order of the bases in a segment of DNA, which contains the information a cell needs to make important molecules like proteins, the functional building blocks of the cell. There are several methods for sequencing, but they all require many copies of the same DNA segment to get accurate results. Fortunately, scientists have developed a technique called polymerase chain reaction, often referred to as PCR, that can quickly and inexpensively create a large number of copies of a DNA segment.

Have you ever been told that you have your mother’s eyes? Or maybe you’ve found that you and your father share a condition such as asthma? People who are biologically related often have similarities in appearance and health because they have some of the same genetic variants. However, you’ve likely noticed that siblings with the same biological parents can differ significantly. Each person’s genome is a combination of DNA from both of their parents, but siblings’ DNA can differ because of the mixing and matching involved in creating reproductive cells.

Even though scientists have been studying genetics since the mid-19th century, they continue to make new discoveries about genes and how they impact our health on a regular basis. NIGMS researchers study how genes are expressed and regulated, how gene variants with different “spellings” of their genetic code affect health, and much more. Get the drop on DNA and the gist of genes with these fast facts:

Genetics is the study of genes and heredity—how traits are passed from parents to children through DNA. A gene is a segment of DNA that contains instructions for building one or more molecules that help the body work. Researchers estimate that humans have about 20,000 genes, which account for about 1 percent of our DNA. The remainder of the DNA plays a role in regulating genes, and scientists are researching other potential functions.

The earliest Andrew Santiago-Frangos, Ph.D., remembers being interested in science was when he was about 8 years old. He was home sick and became engrossed in a children’s book that explained how some bacteria and viruses cause illness. To this day, his curiosity about bacteria persists, and he’s making discoveries about CRISPR—a system that helps bacteria defend against viruses—as a postdoctoral researcher and NIGMS-funded Maximizing Opportunities for Scientific and Academic Independent Careers (MOSAIC) scholar at Montana State University (MSU) in Bozeman.

Becoming a Biologist

Although Dr. Santiago-Frangos wanted to become a scientist from a young age and always found biology interesting, by the time he was attending high school in his native country of Cyprus, he had developed a passion for physics and thought he’d pursue a career in that field. However, working at a biotechnology company for a summer changed his mind. “That experience made me want to dive into biology more deeply because I could see how it could be directly applied to human health. Physics can also be applied to human health, but, at least at that time, biology seemed to me like a more direct way to help humanity,” says Dr. Santiago-Frangos.

“One of the biggest things I hope for in my career is that in 20 years, I still feel the same joy and enthusiasm for research and training that I feel now,” says Prabodhika Mallikaratchy, Ph.D., a professor in the department of molecular, cellular, and biomedical sciences at the City University of New York (CUNY) School of Medicine. Dr. Mallikaratchy talks with us about her career path, research on developing new immunotherapies and molecular tools using nucleic acids, and her belief in the importance of being passionate about your career.

Q: How did you first become interested in science?

A: Growing up in Sri Lanka, I was always a curious child. I remember being drawn to science and math, but there was no particular incident that sparked my interest. By the time I reached high school, though, I had become especially interested in chemistry.

You might first think about sports when you hear the word base, but not all bases are on the baseball diamond. In chemistry, a base is a molecule that reacts with an acid, often by accepting a proton from the acid or from water. Baking soda and dish soap are common bases.

The year 2022 marked 50 years since the creation of the NIGMS Human Genetic Cell Repository (HGCR) at the Coriell Institute for Medical Research in Camden, New Jersey. The NIGMS HGCR consists of cell lines and DNA samples with a focus on those from people with rare, heritable diseases. “Many rare diseases now have treatments because of the samples in the NIGMS HGCR,” says Nahid Turan, Ph.D., Coriell’s chief biobanking officer and co-principal investigator of the NIGMS HGCR. She gives the example of a rare disease advocacy group who worked with the NIGMS HGCR to establish a cell line several decades ago. It was used to identify a gene associated with the disease, which aided in the development of five treatments that have received approval from the Food and Drug Administration.

Researchers have also studied NIGMS HGCR’s samples to help advance knowledge of basic biology and genetics, and even to support the development of a vaccine for a deadly virus.

“DNA is an amazingly beautiful molecule, and it’s so important. Each of our cells has only one copy of DNA, and if it gets damaged, that messes up everything else in the cell,” says Alexis Komor, Ph.D., an assistant professor of chemistry and biochemistry at the University of California, San Diego (UCSD). Check out the highlights of our interview with Dr. Komor to learn about her scientific journey, research on DNA, and advice for students.

Q: How did you decide to study chemistry?

A: I really enjoyed math and science in middle and high school. When I applied to college, I knew I wanted to major in science over math because I felt like it was more relevant to what we experience on a day-to-day basis. I ultimately went into chemistry for a silly reason, but looking back now, I’m so very grateful that I did. Chemistry has this nice balance because it allows you to not only understand how things work on a molecular level but also see how those molecular workings relate to everyday phenomena—for example, understanding how DNA damage on a molecular level can lead to negative health outcomes.