Biochemistry 3380G Lecture Notes - Guanine, Thymine, Ribose
6 Dec 2012
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Document Summary
This was the first piece of evidence for the double helical dna model. The diffraction pattern suggests a double-helix with a periodicity of 3. 4 nm containing 10 repeating units. This was done by taking dna and crystallizing them (shooting x rays through them). This second piece of evidence determined the dna double helix to have 10 repeating units within each 3. 4 nm. The third piece of evidence was that there are two different forms or states that bases can adopt. This was influential as watson and crick were not sure as to which form of the bases occurred naturally in. In the figure above, the left tautomer is the predominant form of bases in life. B-dna is the most common conformation of dna. Also, the phosphates are negatively- charged and are far apart from each other. The two forces stabilizing the double helix are hydrophobic interactions and base-pairing.
