Photograph 51

As it is 93 years ago today that Rosalind Franklin was born, Deskarati thought it would be a good time to re-visit the story of Photograph 51 and the amazing work done by her back in the early fifties.

Rosalind_FranklinPhoto 51 is the nickname given to an X-ray diffraction image of DNA taken by Rosalind Franklin in 1952 that was critical evidence in identifying the structure of DNA. The photo was taken by Franklin while working at King’s College London in Sir John Randall’s group.

James D. Watson was shown the photo by Maurice Wilkins, who had been given it by Raymond Gosling; this occurred without Franklin’s knowledge (Wilkins and Franklin fought frequently), and whether this was or was not with Franklin’s approval is unclear. Along with Francis Crick, they used Photo 51 to develop the first chemical model of DNA, for which the three men jointly won the 1962 Nobel Prize in Physiology or Medicine. As the Nobel prize is not awarded posthumously, Franklin, who had died in 1958, was not eligible for nomination.


Photograph 51

The photograph provided key information that was essential for developing a model of B-form (hydrated) DNA. In particular, it could be determined from the diffraction pattern, and was openly discussed by Franklin in lectures attended by Watson and in reports accessible to Watson and Crick, that DNA (1) was helical, (2) was likely a double helix with antiparallel strands, and, (3) had the phosphate backbone on the outside (thus the bases of DNA, which are the “code” for inheritance, were on the inside of the helix). Calculations from the photograph also provided crucial parameters for the size of the helix and its structure, all of which were critical for the molecular modeling undertaken by Watson and Crick.

Photo 51 was, therefore, the critical data that led to the model and confirmation of the postulated double helical structure of DNA, published during 1953 in a series of five articles in the journal Nature. Franklin and Raymond Gosling’s own publication in the same issue of Nature was the first publication of this more clarified X-ray image of DNA.

DNA_animationAs historians of science have reexamined the period during which this image was obtained, considerable controversy has arisen over both the significance of the contribution of this image to the work of Watson and Crick, as well as the methods by which they obtained the image. Franklin was hired independently of Maurice Wilkins, who, nonetheless, showed Photo 51 to Watson and Crick without her knowledge. Whether Franklin would have deduced the structure of DNA on her own, from her own data, had Watson and Crick not obtained her image, is a hotly debated topic, made more controversial by the negative caricature of Franklin presented in Watson’s novel, “The Double Helix.” Watson later admitted his distortion of Franklin in his book, noting in a preface to a later edition: “Since my initial impressions about [Franklin], both scientific and personal (as recorded in the early pages of this book) were often wrong… Via wikipedia

Deskarati recommends watching the 1987 Horizon TV Film ‘Life story’ starring a very young Jeff Goldblum, its fantastic! Here’s a clip


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