Rosalind Franklin explored the basic shape of DNA with X-ray crystallography, a way of photographing the complex shadows cast by molecules bathed in X-rays. When James Watson saw Franklin’s “photograph 51” of DNA, his “jaw fell open and his heart began to race,” because he could see that a helical structure was responsible for the X-ray pattern. Using her data, James Watson and Francis Crick showed that DNA’s structure is a double helix.

Rosalind Franklin (1920–1958) was born into a prominent London banking family where all children—girls and boys—were encouraged to develop their individual aptitudes. She attended St. Paul’s Girls School, one of the few schools in London where girls were taught science. Then she proceeded to Newnham College, one of the women’s colleges at Cambridge University.

She completed her degree in 1941 and undertook graduate work at Cambridge with Ronald Norrish, a future Nobel Prize winner. She resigned her position in one year in order to contribute to the war effort at the British Coal Utilization Research Association. There she performed fundamental investigations on the properties of coal and graphite. She returned briefly to Cambridge, where she presented a dissertation based on this work and was granted a Ph.D. in physical chemistry. After the war, through a French friend, she gained an appointment at the Laboratoire Centrale des Services Chimiques de l’Etat in Paris, where she was introduced to the technique of X-ray crystallography and rapidly became a respected authority in this field. Her three years in Paris were ones that she remembered fondly—where her professional relationships and her social life were rewarding.

In 1951 she returned to England to the group at King’s College, University of London, assembled by the physicist John Randall to study DNA. She arrived when one of her new colleagues, physicist Maurice Wilkins, was on vacation and major misunderstandings commenced about just what her role would be in the research group—to work independently or just to provide data to Wilkins. She also had to cope with a reduction in social interactions in England compared with her French experience; for example, the men in the laboratory at King’s College could eat lunch in the men’s “commons,” but the women scientists had nowhere to go. It was in this atmosphere that her work was transmitted by Wilkins without her permission to Watson and Crick. When these two submitted their famous article about the molecular structure of DNA to the journal Nature, its editor requested Wilkins and Franklin to submit articles of their own establishing their role in the discovery of the double helix.

After the DNA articles, Franklin went to Birkbeck College, London, to work in J. D. Bernal’s laboratory—a much more congenial setting for her than King’s College. Before her untimely death in 1958 from ovarian cancer, she made important contributions to the X-ray crystallographic analysis of the structure of the tobacco mosaic virus—a landmark in the field. By the end of her life, she had become friends with Francis Crick and his wife and had moved her laboratory to Cambridge, where she undertook dangerous work on the poliovirus.

In 1962 James Watson, Francis Crick, and Maurice Wilkins jointly received the Nobel Prize in medicine or physiology for their determination in 1953 of the structure of DNA. The Nobel Prize can only be awarded to living scientists, a rule that excluded Franklin.

Secret of Photo 51, a PBS Web site relating to the Nova television show about Franklin by the same name.