1) The strongly acidic nature of DNA poses a problem. Why do Watson and Crick think that the DNA âdyadâ, formed by hybridization of two negatively charged molecules, will be 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 issue that you have identified. Figure 6, reproduced from:
 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 is necessary?
5) Did Watson and Crick say too much or too little about the process of replication? Explain your view on this.
1) The strongly acidic nature of DNA poses a problem. Why do Watson and Crick think that the DNA âdyadâ, formed by hybridization of two negatively charged molecules, will be 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 issue that you have identified. Figure 6, reproduced from:
 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 is necessary?
5) Did Watson and Crick say too much or too little about the process of replication? Explain your view on this.
