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Genetics Assignment - Watson and Crick Questions

The 1953 article by Watson and Crick is notable for illuminating the molecular structure of DNA, and for additional observations about the properties of DNA that continue to resonate. For each question below, formulate an answer based on the appropriate section of the article.

Article - Molecular Structure of Nucleic Acids - A structure for Deoxyribose Nucleic Acid.

1) The strongly acidic nature of DNA poses a problem. Why do Watson and Crick think that the DNA "dyad", formed by hybridization of two negatively charged molecules, is stable?

2) Watson and Crick refer to a model proposed by Pauling and Cory. Pauling and Cory proposed a triple helix with phosphates in the center (triangles in the figure below), and bases radiating outwards. A figure from their paper, viewing this structure end on, is shown below. List at least three different aspects of this model that are chemically improbable, or fail to accommodate information about DNA that was available in 1953, when the Pauling and Cory and Watson and Crick models were published. For each problem, explain if, and how, the Watson and Crick model overcomes the problem that you have identified with the Pauling and Cory structure below.

3) What are tautomeric forms, and why did they pose a problem for the Watson and Crick model? Do you think that Watson and Crick adequately addressed the problem of tautomers?

4) RNA and DNA have different helical conformations. Why do Watson and Crick suggest that this occurs?

5) Did Watson and Crick say too much or too little about the process of replication? Explain your view on this.

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