Watson and Crick's calculations from Gosling and Franklin's photography gave crucial parameters for the size and structure of the helix.
The outside of the DNA chain has a backbone of alternating deoxyribose and phosphate moieties, and the base pairs, the order of which provides codes for protein building and thereby inheritance, are inside the helix. The diffraction pattern determined the helical nature of the double helix strands ( antiparallel).
The photograph provided key information that was essential for developing a model of DNA. Likewise, Gosling's work was not cited by the prize committee. The prize was not awarded to Franklin she had died four years earlier, and although there was not yet a rule against posthumous awards, the Nobel Committee generally does not make posthumous nominations. In 1962, the Nobel Prize in Physiology or Medicine was awarded to Watson, Crick and Wilkins. Their model, along with papers by Wilkins both and colleagues, and by Gosling and Franklin, were first published, together, in 1953, in the same issue of Nature. Watson and Crick used characteristics and features of Photo 51, together with evidence from multiple other sources, to develop the chemical model of the DNA molecule. Watson recognized the pattern as a helix because his co-worker Francis Crick had previously published a paper of what the diffraction pattern of a helix would be. Randall, the head of the group, had asked Gosling to share all his data with Wilkins. Rosalind Franklin did not know this at the time because she was leaving King's College London. When it had been decided that Franklin would leave King's College, Gosling showed the photograph to Maurice Wilkins (who would become Gosling's advisor after Franklin left).Ī few days later, Wilkins showed the photo to James Watson after Gosling had returned to working under Wilkins' supervision. Use in discovering structure of DNA Īccording to Raymond Gosling's later account, although photo 51 was an exceptionally clear diffraction pattern of the "B" form of DNA, Franklin was more interested in solving the diffraction pattern of the "A" form of DNA, so she put Gosling's photo 51 to the side. It was critical evidence in identifying the structure of DNA. The image was tagged "photo 51" because it was the 51st diffraction photograph that Franklin had taken. Photo 51 is an X-ray based fiber diffraction image of a paracrystalline gel composed of DNA fiber taken by Raymond Gosling, a graduate student working under the supervision of Rosalind Franklin in May 1952 at King's College London, while working in Sir John Randall's group.
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