History of molecular biology Crick and Watson built physical models using metal rods and balls, in which they incorporated the known chemical structures of the nucleotides, as well as the known position of the linkages joining one nucleotide to the next along the polymer. At King's College Maurice Wilkins and Rosalind Franklin examined X-ray diffraction patterns of DNA fibers. Of the three groups, only the London group was able to produce good quality diffraction patterns and thus produce sufficient quantitative data about the structure. In 1948 Pauling discovered that many proteins included helical (see alpha helix) shapes. Pauling had deduced this structure from X-ray
Francis Crick diffraction images collected by Franklin provided the best evidence for the helical nature of DNA. While Franklin's experimental work proved important to Crick and Watson's development of a correct model, she herself could not realize it at the time. When she left King's College, Director Sir John Randall insisted that all DNA work belonged exclusively to King's and ordered Franklin to not even think about it. Franklin subsequently did superb work in J. D. Bernal's Lab at Birkbeck College with the tobacco mosaic virus extending ideas on helical construction. Crick was often described as very talkative, with Watson – in