Some might think that protein is only important for weightlifters. In truth, all life relies on the activity of protein molecules. A single human cell contains thousands of different proteins with diverse roles, including:

• Providing structure. Proteins such as actin make up the three-dimensional cytoskeleton that gives cells structure and determines their shapes.
• Aiding chemical reactions. Many proteins are biological catalysts called enzymes that speed up the rate of chemical reactions by reducing the amount of energy needed for the reactions to proceed. For example, lactase is an enzyme that breaks down lactose, a sugar found in dairy products. Those with lactose intolerance don’t produce enough lactase to digest dairy.
• Supporting communication. Some proteins act as chemical messengers between cells. For example, cytokines are the protein messengers of the immune system and can increase or decrease the intensity of an immune response.

To make naturally colorless biological structures easier to study, scientists often use fluorescent tags and other tools to color them. Here, we feature images with purple hues and pair them with questions to test your knowledge of basic science concepts.

Visit our image and video gallery for more scientific photos, illustrations, and videos in all the colors of the rainbow.

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.

When she started college, Anne Carpenter, Ph.D., never guessed she’d one day create software for analyzing images of cells that would help identify potential medicines and that thousands of researchers would use. She wasn’t planning to become a computational biologist, or even to focus on science at all, but she’s now an institute scientist and the senior director of the Imaging Platform at the Broad Institute of Massachusetts Institute of Technology (MIT) and Harvard in Cambridge.

Starting Out in Science

Before beginning her undergraduate studies at Purdue University in West Lafayette, Indiana, Dr. Carpenter’s strongest interests were reading and writing. Then, her subjects expanded. “In college, I liked science as much as anything else, and I realized that was unusual, as a lot of other people really struggled with it. I decided to pursue science because I enjoyed it and the field had good job prospects,” she says. Dr. Carpenter majored in biology because she felt it had the “juiciest questions” as well as a direct impact on human health.

Every year on March 14, many people eat pie in honor of Pi Day. Mathematically speaking, pi (π) is the ratio of a circle’s circumference (the distance around the outside) to its diameter (the length from one side of the circle to the other, straight through the center). That means if you divide the circumference of any circle by its diameter, the solution will always be pi, which is roughly 3.14—hence March 14, or 3/14. But pi is an irrational number, which means that the numbers after the decimal point never end. With the help of computers, mathematicians have determined trillions of digits of pi.

To celebrate Pi Day, check out this slideshow of circular microbes, research organisms, and laboratory tools (while you enjoy your pie, of course!). To explore more scientific photos, videos, and illustrations, visit our image and video gallery.

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.

“Being a researcher is special because there aren’t many jobs that allow you to spend the majority of your time thinking about the things you find the most interesting in the whole world,” says William Ratcliff, Ph.D., an associate professor of biological sciences and the director of the interdisciplinary graduate program in quantitative biosciences at Georgia Institute of Technology (Georgia Tech) in Atlanta. We talked with Dr. Ratcliff about his career path, research on yeast, and advice to budding scientists.

Q: How did you first become interested in science?

A: My family owns land in Northern California that has been passed down for more than 100 years. When I was a child, my brother and I would spend summers on that land getting lost in the woods. We would really see the forest for its parts: seeing how organisms interacted with one other, tracking stages of development, and listening to birdcalls. My grandmother would identify plants by their scientific names, and we’d discuss their reproduction strategies. We became amateur natural historians during those summers. Perhaps it’s no surprise my brother and I both got Ph.Ds. in biology.

Just as electricity powers almost every modern gadget, the tiny molecule adenosine triphosphate (ATP) is the major source of energy for organisms’ biochemical reactions. ATP stores energy in the chemical bonds that hold its three phosphate groups together—the triphosphate part of its name. In the human body, ATP powers processes such as cell signaling, muscle contraction, nerve firing, and DNA and RNA synthesis. Because our cells are constantly using and producing ATP, each of us turns over roughly our body weight in the molecule every day!

Our bodies can produce ATP in several ways, but the most common is cellular respiration—a multistep process in which glucose molecules from our diet and oxygen react to form water and carbon dioxide. The breakdown of a single molecule of glucose in this way releases energy, which the body captures and stores in around 32 ATP molecules. Along with oxygen, mitochondria are crucial for producing ATP through cellular respiration, which is why they’re sometimes called the powerhouses of cells.

The word culture may make you think of a flag, style of clothing, celebration, or some other tradition associated with a particular group of people. But in biomedical science, a culture is a group of cells grown in a lab. Scientists use cultures to learn about basic biological processes and to develop and test new medicines.

The Birth of a Culture

Scientists can grow many types of cells as cultures, from bacteria to human cells. To create a culture, a researcher adds cells to a container such as a Petri dish along with a mix of nutrients the cells need to grow and divide. The exact recipe varies depending on the cell type. (Because many lab containers were historically made of glass, researchers sometimes refer to studies that use cultures as in vitro—Latin for “in glass.”) Once the cells multiply and fill their container, researchers split the culture into new containers to produce more.