PCB 4674 Lecture Notes - Lecture 3: Reverse Transcriptase, Thermal Fluctuations, Mutation Rate
2 Sep 2016
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Document Summary
Alleles slightly different forms of the same gene often produce proteins that are functional but which differ from original version in some way. Arise when one or more bases in parental strand is changed and repair mechanisms fail to identify and / or correct. Two major sources replication errors damage to dna before or after replication. Rate of replication mistakes far exceeds rate of mutation. Proofreading mechanisms operate during replication to identify and correct error. Occasional changes to dna sequences benefit a species over the long-term but individual survival requires genetic stability. Change in dna sequence = mutation represents a failure of repair mechanisms rate at which mutations occur = mutation rate: maintenance of dna sequences. E. coli ~ 1 base / 109 nucleotides / generation: mammalian mutation rate ~ 1 aa/200k years in most cases, ~ 1 base / 109 nucs / replication.
