Book Report on Double Helix

Maria Navarrete
1/2- Ms. Baker

The Double Helix
Watson began to form interest in the structure of DNA after coming across Maurice Wilkins X-ray diffraction picture. Watson thought that if the structure was founded then genes would better be understood after finding out those genes could crystallize. Along with Crick, Watson traveled to Oxford to overhear Franklin’s talk on x-ray pictures she had come across and formulated that a 3-chain helix fit seemed reasonable. More research came through when Austrian chemist Erwin Chagraff identified DNA to have purine and pyrimidine bases. Peter Pauling described a 3 chain helix with a sugar phosphate background at the center and also figured out that protein folding had alpha-helices. Watson did not agree with one of Pauling’s finding and was determined to find a 2 chain helix instead and study the chemistry of bases. Franklin found out that DNA contained water which led to thinking that since living cells are mostly in water, DNA must interact with water as well. Franklins suspicions were correct because in order to for DNA to have the same structure as living cells then there must be a high water content. Crick and Watson construct their first attempt of a DNA molecule but failed with no evidence to support their findings, the magnesium salt bridge included would not function with a molecule surrounded by water with water interactions lifting the atom from the bridge and breaking the helix.  
The scientists experimented in a variety of ways especially with model buildings. Pauling discovered protein folding with model buildings of paper and wire creating the polypeptide chains in amino acids and twisting them into several shapes until one came close to an x-ray pattern. Watson chose to follow Pauling’s way of model building instead of experimentation to figure out the structure. Another way of experimentation could be the x-ray pictures given crystallization which gave the scientists a...