Rosalind Franklin

Rosalind Elsie Franklin (1920-1958) was born on 25 July 1920 in London and was educated at St Paul's Girls' School before attending the University of Cambridge in 1938. At the age of 22, she gave up her fellowship to take her first position as a physical chemist at the British Coal Utilization Research Association in London.

In 1947, Franklin went to Paris to work under Jacques Méring, learning X-ray crystallographic methods and to continue research into carbon. In 1951, she moved to King's College, London, to work on DNA by making very thin threads of it, bundling them and hitting them with a super-fine X-ray beam. She soon discovered the two forms of DNA. The easily photographed A form was dried, while the B form was wet. While much harder to photograph, her pictures of the B form showed a helix. Since the water would be attracted to the phosphates in the backbone, and the DNA was easily hydrated and dehydrated, she guessed that the backbone of the DNA was on the outside and the bases were therefore on the inside. This was a major step forward in the search for the structure of DNA.

In November 1951, Franklin presented her A and B form data to an audience that included James Watson, who was working in Cambridge with Francis Crick on the X-ray crystallography of protein. On hearing her lecture, the two men built their first model of DNA: a triple helix with the bases on the outside. However, in May 1952, Franklin got her first good photograph of the B form of DNA, showing a double helix. This was another major breakthrough. Franklin then continued working on the A form as it provided more data.

In early 1953, Watson and Crick saw some draft work by the American Linus Pauling and were given access to Franklin's data and B form photographs that showed DNA to be a multiple helix. From his work on proteins, Crick realized that her data implied an antiparallel double helix. Franklin had reached this conclusion with regards to the A form, but had yet to apply this theory to the other form.

Franklin moved to Birkbeck College, London, where she continued some work on DNA and was given charge of a virus research group. Between 1953 and 1958 she published 17 papers on viruses, laying the foundations of structural virology and establishing the relationship between ribonucleic acid (RNA) and protein (the virus coat protein) for the first time.

Diagnosed with ovarian cancer in 1956, in her last years she continued research on a polio virus, but died on 16 April 1958, aged 37, within minutes of her last paper being read at the Faraday Society.

image: Science Photo Library