Photo 51

Rosalind Franklin did not have anything to do with the discovery of the helical structure of DNA. Feminists constantly whine about this, but the history is quite clear. Franklin didn't get a Nobel prize because Franklin didn't deserve a Nobel prize.

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. Now, some may say that the honor belongs to Franklin, because she supervised Gosling's work. But that isn't true.

Gosling had made the first x-ray diffraction image of crystallized DNA under the direction of Wilkins. His comment on this discovery was "I must be the first person ever to make genes crystallize", although he was probably unaware of the prior work of Florence Bell. In any case, he was already doing x-ray diffraction of DNA before Franklin ever appeared on the scene.

After the initial work producing the first x-ray diffraction of DNA, Randall reassigned Gosling to work with Rosalind Franklin, who had been just hired to join King's College in 1951. When Gosling made the photo, Franklin handed it to Wilkins, who soon handed it to Watson. That photo, along with a report that included the space group values of the crystal, gave Crick everything he needed. By the time Watson and Crick saw both, Rosalind Franklin had already moved onto another lab to study the tobacco mosaic virus. She wasn't even around when Crick put the pieces together.

"Crick had laboriously worked out how to solve the so-called phase problem when diffraction is from a helix, since the standard Patterson functions do not apply. Thus, technically a graduate student at the time, he had the good fortune to be in a perfect position to understand what Franklin could not possibly have seen in the pattern.

Armed with Crick's insight, all that remained was for Watson to get the base-pairing (after a misstep corrected by a lab member)."

Update: Additional information here.