How Did Watson And Crick Think That The DNA Dyad

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1. Watson and Crick think that the DNA “dyad” formed by hybridization of two negatively charged molecules will be stable because of the hydrogen bonding. The hydrogen atoms have a partially positive charge that stabilized the partially negatively charged Oxygen and Nitrogen. This weak interaction makes the hydrogen bonds and when there is a large amount of these weak bonds, the helix will be very stable.
2. When Pauling and Cory attempted to come up with the structure of DNA, they thought that the DNA helix was a triple helix. This was because they misinterpreted DNA A structure and concluded that the phosphate and sugars were on the inside and the nucleotide bases were on the outside. Watson and Crick said this was not possible because phosphates can’t fit together inside the helix without breaking their molecular bonds. The studies Watson and Crick made were based off of DNA B molecule from the X-ray of DNA B taken by Rosalind Franklin that had low concentration, rather than A DNA which was high in salt concentration that gave Pauling an improper representation of the DNA helix. Pauling and Cory stated that the helix was made of three helices, Watson and Crick disapproved of this concept because phosphate backbones are negatively charged, it was impossible to put three negatively charged strands with each
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Tautomeric forms are when Isomers have different positions of protons and electrons, Hydrogen would transfer and make a single bond to a double bond, and vice versa. In this case, there was a keto-enol tautomerization. This tautomerization could cause mispairing of bases of DNA. For example, there could be an enol tautomer pairs of A and G, T and C, and A and C mispairings. Incorrect base pairing can cause many genetic mutations, including cancer. Watson and Crick assumed that each base pair was in its Keto form instead of Enol form, and that each purine was paired with a pyridine perfectly. They did not address whether or not tautomers could cause a
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