The Double Helix: James Watson And Francis Crick

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Today, the 1953 discovery of the double helix, “the twisted-ladder structure” of DNA, by James Watson and Francis Crick, constitutes one of the greatest breakthroughs in the history of science. The discovery has given rise to the molecular biology of today and generated new insights into genetic coding upon which today’s multi-billion dollar biotechnology industry is founded. It laid the groundwork for other scientific achievements, including modern forensics and the mapping of the human genome. All of this is thanks to Watson and Crick, and their groundbreaking discovery of “the master molecule of life” (Dahm, 2011, p. 327).
Genetics Before the Discovery
Before Watson and Crick’s breakthrough, in the early 1950’s, scientists used the term
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Neither genetics nor reproduction could be fully understood without such information. For eighteen months, they pursued the knowledge with a single-minded focus, immersing themselves in all fields of science concerned, including genetics, chemistry, physical chemistry, biochemistry, and X-ray crystallography. They took especial interest in earlier genetic study.
Early genetic research included that of Biochemist Erwin Chargaff, who had composed Chargaff’s rules. His rules stated that among DNA’s four bases adenine (A) and thymine (T) always appeared in ratios of one-to-one as did guanine (G) and cytosine (C). Two other researchers, Maurice Wilkins and Rosalind Franklin, had gotten X-ray images of DNA that suggested a helical, spiral shape (“The Francis Crick Papers,” 2013).
To create their models, Watson and Crick adopted the model-building technique, developed by American chemist Linus Pauling. To determine the structure of molecules, Pauling used pieces, shaped according to the known characteristics of the atom it represented. Then, he manipulated the pieces to figure out the most logical way for them to fit together (Aaseng, 1984, p.
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In accordance with Donohue's advice, Watson fixed the model, putting the bases into their correct form in cardboard models. While shifting around the new accurate molecules on his office table, Watson discovered that when A was joined with T, they resembled a combination of C and G and that each pair could unite by forming hydrogen bonds. If A always paired with T and likewise, C with G then not only were Chargaff's rules accounted for, but the pairs could fit precisely between the two helical sugar-phosphate backbones of DNA, which formed the outer bars of the ladder. The structural features were the same as the X-ray pictures suggested, and the pairing of the bases allowed the backbones to pass in opposite directions to each other, also as the X-rays indicated.
Watson and Crick Publicize Their Findings
Watson and Crick published their findings, titled "A Structure for Deoxyribose Nucleic Acid," in the British scientific weekly Nature on April 25, 1953. The report included a drawing of the double helix, as depicted by Crick's wife. In the paper, they described the pairing of bases inside the two DNA backbones so that A combines with T and C with G. They suggested that the pairing rule was a copying mechanism for DNA. The sequence of the

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