BIO SCI 97 Lecture Notes - Lecture 1: Semiconservative Replication, Uracil, Guanine
2 Apr 2018
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Document Summary
There has to be a possibility of change because change and variability is the basis for why we are here today. If dna did not undergo variation, there would be no variation for evolution to act on- there would just be nucelotides replicating each other. Purines: adenine and guanine, and have two rings. Pyramids: cytosine and thymine, and have three rings: nucleotides can be polymerized, and polymerization always occurs from the 5 end to the three end. Dna polymerase adds nucleotides from 5 to 3: uracil is present in rna, not in dna. Rna is much less stable than dna is. Rna needs to be unstable, thanks to the hydroxyl group that is present in rna: hydrogen bonds can form between the bases, gc form 3 hydrogen bonds, while at forms 2 hydrogen bonds. In dna molecule, you have thousands of bases that hold hydrogen bonds that are suf cient to hold the bases.
