Women in Science: Rosalind Franklin and the Discovery of DNA

Do you know the story behind the discovery of the double helix structure of our DNA? In honor of International Women's Day, let's highlight the efforts of Rosalind Franklin, a woman who was almost written out of history despite laying the foundation for our understanding of the structure of our genetic makeup.

Sabrina Stierwalt, PhD
Episode #183

Today is International Women’s Day, a day for celebrating the ways in which women have shaped culture and progressed our knowledge of the world around us. It is also a day for drawing attention to the obstacles women still face by promoting discussions of how to work to remove those obstacles to an international stage.

When I complained to my middle school science teacher that all we ever learned about were discoveries made by men and asked him why we couldn’t talk about an experiment led by a woman for a change, he told me that historically, women hadn’t participated in scientific pursuits.

My teacher wasn’t all wrong. There have been (and continue to be) societal pressures and barriers to women’s participation in scientific research. Prior to the 1860s, few universities in the U.S. even admitted women. The first woman to earn a PhD in physics in the United States, Jenny Rosenthal Bramley, did so in 1929.

But that’s not the whole story. Women have always participated in science at some level, but their contributions were not always valued. In some cases, they were forced to work in the shadows of male peers, or even their spouses, so their results had a male name on them as well. In the worst cases, credit for women’s research was given to male colleagues and women were written out of history entirely.

One of the more egregious examples is the lack of credit originally given to Rosalind Franklin for uncovering the structure of DNA. Born in 1920 (the first year Oxford began awarding degrees to women), Rosalind Franklin used the technique of X-ray crystallography to uncover the structures of viruses, coal, graphite, and, perhaps most famously, DNA and RNA.

What Is DNA?

DNA, or deoxyribonucleic acid, is a molecule that contains all of our hereditary information, our unique genetic code. DNA can also replicate, meaning that it can make copies of itself. This is incredibly important for our origin and growth as a species. When our bodies need to create new cells, copies of our DNA from existing cells can be transferred. Our brain cells tend to last our entire lives, but other kinds of cells tend to have much shorter lifetimes, like red blood cells (several months) or skin cells (only a few weeks), and so must be replaced.

Research that began with Franklin, as well as work by James Watson, Francis Crick, and Maurice Wilkins, led to the discovery of the double helix structure of DNA in 1953. (Although we should note that DNA was actually identified in 1869 by Frederich Miescher.) You can think of a double helix as a twisted ladder.

The rungs of the ladder are formed by two possible pairs of nitrogen bases: either adenine and thymine or guanine and cytosine. The sides holding the ladder together are made up of phosphate and sugar molecules. The order and pattern in which these base pairs appear holds the genetic information unique to each of us, much like how letters can be assembled in different ways to form words and sentences.  This information can be translated by a messenger molecule known as ribonucleic acid, or RNA, into the actual production of proteins. These long strings of bases are able to fit into our cells by being packed into chromosomes.

Knowing the structure of DNA allows us, among many other benefits, to better identify which human disorders are genetic. We can then perform important genetic tests from determining which genetic mutations a person could pass onto their children and when we are at risk for a genetic disease.


About the Author

Sabrina Stierwalt, PhD

Dr. Sabrina Stierwalt is an extragalactic astrophysicist at the California Institute of Technology and Adjunct Faculty at the University of Virginia.

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