We couldn’t survive without proteins. They’re essential molecules that provide cells with structure, aid in chemical reactions, support communication, and much more. Portion out protein numbers with us below!

10 Trillion

That’s how many proteins scientists estimate are in each human cell.

229,378

That’s how many structures researchers shared with the scientific community through the Protein Data Bank (PDB) from its establishment in 1971 to the end of 2024. The PDB is a global repository for 3D structural data of proteins, DNA, RNA, and even complexes these biological molecules form with medicines or other small molecules.

42

That’s the percent of your body weight (not counting water) that’s made up of proteins.

“I think there’s a very creative side to science, in figuring out how to approach a problem, which I find really engaging,” says Mia Huang, Ph.D., an associate professor of chemistry at the Scripps Research Institute in La Jolla, California. In an interview, Dr. Huang discussed her shift in interest from medicine to science, her graduate school work on nature-inspired antifreeze molecules, and her lab’s exploration of the roles of sugar-coated proteins in our bodies.

“I remember thinking in my first cellular biology class how impossibly beautiful it is that there are tiny machines in our bodies doing work,” says Morgan DeSantis, Ph.D., an assistant professor of molecular, cellular, and developmental biology at the University of Michigan in Ann Arbor. We talked with Dr. DeSantis about how her career in science almost didn’t happen, how happy she is that it did, and what she’s learning through her research on molecular machines.

Q: How did you become interested in science?

A: I wasn’t remotely interested in science in high school—I was a self-identified artist. I went to the College of Wooster in Ohio with the sole purpose of studying art and doing pottery. But one day during my freshman year, a box with all the pieces I made throughout the year fell, and everything inside broke. It’s hard to describe the emotions I felt that day, but something changed in me, and I realized pottery wasn’t for me. I couldn’t start the projects over, and I didn’t want to drop out and move back home. So, I decided to become a medical doctor.

Every day, our cells must produce all the various molecules they need to stay alive. But the chemical reactions to create these molecules can’t occur without help—which is where enzymes come in. Enzymes are biological catalysts, meaning they speed up the rate of specific chemical reactions by reducing the amount of energy needed for the reaction to occur. Most enzymes are proteins, but some RNA molecules can also act as enzymes.

Thousands of different enzymes catalyze the vast range of reactions that take place within cells, but each enzyme typically supports one of the following types of tasks:

Happy Valentine's Day! In place of red roses, we hope you'll accept a bouquet of beautiful scientific images featuring rich, red hues. Be sure to click all the way through to see the festive protein flowing through your blood!

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

“There aren’t many professions that can provide this much opportunity for learning, especially when it comes to understanding how our bodies work. I really love what I do—I wouldn’t trade it for anything,” says Alan Saghatelian, Ph.D., a professor in the Clayton Foundation Laboratories for Peptide Biology at the Salk Institute for Biological Studies in La Jolla, California. From studying new facts and experimental techniques to adopting new ways of thinking, researchers never stop learning, and Dr. Saghatelian credits his love for learning and exploring as reasons why he’s perfectly suited for science. He's used these passions to build a successful career in biochemistry.

From Chemistry to Biology

Dr. Saghatelian’s love for chemistry began when he was young. He was drawn to how predictable it could be: Mix two chemical compounds in the same way and they’ll always combine to form the same substance, as dictated by the rules of chemistry.

Copper pipes, copper wires, copper…food? Copper is not only a useful metal for conducting electricity, but it’s also an essential element we need in our bodies for a variety of important activities—from metabolizing iron to pigmenting skin.

Copper is required to keep your body going. Enzymes that use copper are called cuproenzymes, and they catalyze a wide range of reactions, including making neurotransmitters and connective tissue. The element is found on the Statue of Liberty’s covering, in wiring and electronics, and in the blue blood of crustaceans. Credit: Compound Interest CC BY-NC-ND 4.0. Click to enlarge.

The element potassium plays a pivotal role in our bodies. It’s found in all our cells, where it regulates their volume and pressure. To do this, our bodies carefully control potassium levels so that the concentration is about 30 times higher inside cells than outside. Potassium works closely with sodium, which regulates the extracellular fluid volume and has a higher concentration outside cells than inside. These concentration differences create an electrochemical gradient, or a membrane potential.

Potassium is the primary regulator of the pressure and volume inside cells, and it’s important for nerve transmission, muscle contraction, and more. Credit: Compound Interest CC BY-NC-ND 4.0. Click to enlarge.

A career path in science is rarely clear cut and linear, which Elimelda Moige Ongeri, Ph.D., can attest adds to its excitement. She went from working in animal reproductive biology to studying proteins involved in inflammation and tissue injury. Dr. Ongeri is also currently dean of the Hairston College of Health and Human Sciences and professor of physiology at North Carolina Agricultural and Technical State University (NC A&T) in Greensboro. In this interview, she shares details of her career, including a change in research focus to human physiology; her goals for the future; and advice for students.

Q: How did you first become interested in science?

A: I was born and raised in Kenya, and, at that time, junior high students were required to select a path to pursue (e.g., the arts or the sciences) and three specific subjects to focus on. My teachers encouraged me to pursue the science path, and I eventually chose to focus on biology, chemistry, and math. Math was my favorite subject at the time, but I didn’t feel that a math degree could lead to many job opportunities, so I chose to pursue biomedical science.

“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.