Franklin, Rosalind Elsie (1920-1958) was a British chemist and molecular biologist. She made important X-ray studies that contributed greatly to the construction of a groundbreaking model of DNA (deoxyribonucleic acid) built in 1953 by James Dewey Watson and Francis H. C. Crick. In addition, her structural analysis of coals and chars promoted a better understanding of their properties. She also determined the complex structure of the tobacco mosaic virus, which attacks tobacco plants.

Rosalind Elsie Franklin was born in London in 1920. She was the second of five children. She attended St. Paul's Girls' School in London. Franklin then went to Cambridge University to study chemistry. After graduation, she remained at Cambridge to study gas-phase chromatography.

From 1942 to 1946, Franklin worked as an assistant research officer at the British Coal Utilisation Research Association. There she studied the physical structure of coal. In 1945, she earned her Ph.D. degree from Cambridge University for this work.

In 1947, Franklin moved to Paris to work for the Laboratoire Central des Services Chimiques de l'Etat. She remained at the Laboratoire until 1950, learning the techniques of X-ray diffraction, or using X rays to determine the arrangement of atoms in a solid material (in this case, crystals). Franklin used X-ray diffraction to identify the differences between carbons that turn into graphite when heated and those that do not. Her findings contributed to the development of carbon-fiber technology.

In 1951, Franklin began a three-year fellowship with the Medical Research Council (MRC) unit at King's College, London. There she used X-ray diffraction in the lab to study DNA. British biophysicist Maurice Hugh Frederick Wilkins and research student Raymond Gosling had already begun work to determine the structure and function of DNA. But it was Franklin's photographs that would provide the most critical information needed to decipher DNA's structure.

Franklin experimented with changes in the water content of DNA specimens and was able to demonstrate that DNA could exist in two forms: a crystalline form and a wet one. During the same period, biologists James Watson and Francis Crick were conducting DNA research at Cambridge University. Watson and Crick were not doing experiments on DNA. Instead, they were building molecular models.

In January of 1953, Franklin started building a model of DNA with a figure-eight configuration. At the same time, Watson and Crick were speeding the pace of their own model-building, concerned that American scientist Linus Carl Pauling was near completion of similar work and would beat them to announcing the structure of DNA.

Wilkins showed Franklin's X-ray photographs of DNA to Watson, without Franklin's knowledge or permission. This gave Watson and Crick the information they needed to prove that DNA had a helical structure. In April of 1953, Watson and Crick published a seminal article in the British journal Nature, announcing their model for the structure of DNA. The same issue of Nature included an article by Franklin and Gosling summarizing their DNA research. The article was seen as corroborating Watson and Crick's findings, but actually it summarized work that was independent.

In April of 1953, when the article was published, Franklin had not completely deciphered the structure of DNA, but she was close to doing so—in fact, Crick himself would later describe her as having been “only two steps away” from determining the structure. About the same time, Franklin left King's College and went to work at Birkbeck College in London. She began work on the structure of the tobacco mosaic virus (TMV) and started collaborating with scientist Aaron Klug on this research. She determined that the RNA (ribonucleic acid) of the virus— the carrier of the genetic information—formed a long, single chain embedded deep within the protein framework.

Franklin died of cancer in 1958 at 37.

Four years later, Watson, Crick, and Wilkins received the Nobel Prize in medicine or physiology for their work in determining the structure of DNA. Because the Nobel Prize cannot be issued posthumously, Franklin could not have been considered for it. Had she lived, some historians believe she would have been among the honorees.

In 1982, Aaron Klug received the Nobel Prize in chemistry, partly for the work he had begun with Franklin and completed after her death.