The Double Helix Analysis

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The genius of Watson and Crick in The Double Helix is achieved by their synthesis of the work of many (including Jerry Donohue, Maurice Wilkins, and Rosalind Franklin). How they acknowledge this credit is of interest. While all three professionals are named, the manner in which they are thanked varies. Watson and Crick felt “indebted to Dr. Jerry Donohue” whilst “stimulated by a knowledge of the general nature” of the ideas of Wilkins and Franklin.

After extensive research, Watson and Crick concluded that DNA was composed of two intertwined chains with identical base sequences held together with hydrogen bonds. However, building a model based on this theory proved to be a significant task. Watson could not see how common tautomeric forms of guanine would successfully hydrogen bond to adenine. Donohue knew the answer. He pointed out that the configuration of certain tautomeric forms were favored arbitrarilary. In particular, he told Watson that these molecules surely existed in the “keto” form. With this knowledge, Chargaff’s rule (the total abundance of purines is equal to the total abundance of pyrimidines), and several hours of shifting bases in and out of various paring possibilities, Watson found his answer. When an adenine was paired with thymine, and guanine was paired with cytosine, the hydrogen bonds formed naturally. Pairing the bases in this fashion also revealed a systematic relationship between glycosidic bonds that strongly suggested that the backbones of the two chains must run in opposite directions. By using the correct tautomeric forms, the double helix structure made sense, conceptually and visually. Donohue’s information proved to be invaluable.

The manner in which Watson and Crick gave credit to Wilkins, Franklin, and their coworkers at King’s College is quite different. Though they felt “indebted” to Donohue, Watson and Crick were “stimulated by a knowledge of the general nature” of the work at King’s College. While clearly...
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