Francis Crick DNA crystals revealed to Crick that the two DNA strands were antiparallel. In January 1953, Watson was shown an X-ray photograph of B-DNA (called photograph 51), by Wilkins. Wilkins had been given photograph 51 by Rosalind Franklin's Ph.D. student Raymond Gosling. Wilkins and Gosling had worked together in the Medical Research Council's (MRC) Biophysics Unit before director John Randall appointed Franklin to take over both DNA diffraction work and guidance of Gosling's thesis. It appears that Randall did not communicate effectively with them about Franklin's appointment, contributing to confusion and friction between Wilkins and Franklin. In the middle of February
Molecular models of DNA community. After DNA has been separated and purified by standard biochemical methods, one has a sample in a jar much like in the figure at the top of this article. Below are the main steps involved in generating structural information from X-ray diffraction studies of oriented DNA fibers that are drawn from the hydrated DNA sample with the help of molecular models of DNA that are combined with crystallographic and mathematical analysis of the X-ray patterns. A paracrystalline lattice, or paracrystal, is a molecular or atomic lattice with significant amounts (e.g., larger than a few percent) of partial disordering of