Photo-51 is a crystallographic X-ray diffraction image captured by Raymond Gosling, a graduate student working under the supervision of Rosalind Franklin at King's College London in 1952. This photograph played a pivotal role in the discovery of the structure of DNA.
Rosalind Franklin was an expert in X-ray crystallography, a technique used to determine the atomic and molecular structure of a crystal, where the crystalline atoms cause a beam of X-rays to diffract into many specific directions. In 1951, she joined the team at King's College, where Maurice Wilkins was also working on DNA structure. However, there was some misunderstanding or lack of communication about their respective roles, leading to tension between Franklin and Wilkins.
Photo-51 was taken by Gosling, but it was Franklin's expertise that led to the conditions under which the photograph was taken. The image showed an X-shaped pattern, which indicated that DNA had a helical structure. Franklin's analysis of this and other X-ray images helped her deduce that DNA had a helix with two strands and a diameter of about 2 nanometers. She also suggested that the backbones were on the outside with the bases inside, and that the structure was most likely a helix with 10 bases per turn.
The importance of Photo-51 extends beyond the discovery of DNA's structure. It has become symbolic of the contributions of women in science, the ethical considerations in scientific collaboration, and the recognition of unsung heroes in scientific discovery. Franklin's work has been celebrated posthumously, with numerous books, articles, and even a play ("Photograph 51") focusing on her life and contributions.
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