Rosalind Franklin's x-ray diffraction photograph of the B form of deoxyribonucleic acid (q.v.). The photo provided Watson and Crick with certain data essential for constructing their three-dimensional model of DNA. It revealed the molecule to be a helix that undergoes a complete revolution every 3.4 nm with ten nucleotide pairs per turn. The photograph was taken May 1, 1952. See Chronology, Bibliography, Secret of Photo 51.
Reprinted by permission from Nature. R. E. Franklin and R. E. Gosling, Molecular configuration in sodium thymonucleate. Nature 171 (April 25, 1953): 740–741. © 1953 Macmillan Publishers Ltd.
Subjects: Genetics and Genomics.