DNA sequencing 1953, James Watson and Francis Crick put forward their double-helix model of DNA, based on crystallized X-ray structures being studied by Rosalind Franklin – and without crediting her. According to the model, DNA is composed of two strands of nucleotides coiled around each other, linked together by hydrogen bonds and running in opposite directions. Each strand is composed of four complementary nucleotides – adenine (A), cytosine (C), guanine (G) and thymine (T) – with an A on one strand always paired with T on the other, and C always paired with G. They proposed such a structure allowed each strand
Francis Crick without her knowledge or consent by Watson and Crick in their construction of the double helix model of DNA. Of the four DNA researchers, only Franklin had a degree in chemistry; Wilkins and Crick had backgrounds in physics, Watson in biology. Prior to publication of the double helix structure, Watson and Crick had little direct interaction with Franklin herself. They were, however, aware of her work, more aware than she herself realized. Watson was present at a lecture, given in November 1951, where Franklin presented the two forms of the molecule, type A and type B, and discussed the position