lecture outlines for posting8

lecture outlines for posting8 - Lecture 8 EEB 13 31 January...

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Lecture 8 – EEB 13 – 31 January 2008 Dr. Hespenheide kinds of microevolutionary change : - affect kinds/frequencies of alleles - four: mutation, migration. natural selection, genetic drift 1. mutation - two kinds [ chromosomal mutations – discussed Tuesday] gene mutations - to a single gene or allele [remember, genes produce proteins by the triplet code] deletions/insertions – a base pair is lost or added and alters way triplets are read afterward; for example - CAT.TAG.GAT.ACT. .. [C-deleted] ATT.AGG.ATA.CT. ... called a “ nonsense ” mutation, creates a very damaged enzyme, usually always a “bad” mutation substitutions - change in only one base pair - example: sickle-cell anemia - mutation to β Hb (146 aa’s) position 6: triplet C T C (codes for glutamic acid) C A C (valine) silent mutations - change in DNA but no change in protein, because triplet code is “redundant”; i.e. , an amino acid is coded for by more than one triplet - β Hb position 6, triplet CT C (glutamic acid) CT T (glutamic acid) neutral mutations - change in protein but no change in function [- not neutral at critical positions - active sites, amino acids affecting folding] - neutral at non-critical positions (”space fillers”) - allows important alternative form of evolution to Darwinian evolution - later effect of mutation: rarely beneficial, usually harmful or neutral rate of mutation: - rare - 1/1,000,000 (10 -6 ) individuals/loci/generations - mutation rates are affected by environmental radiation such as ultraviolet radiation in sunlight; ultraviolet radiation is mostly absorbed by
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This note was uploaded on 04/16/2008 for the course EE BIOL 13 taught by Professor Hespenheide during the Winter '08 term at UCLA.

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lecture outlines for posting8 - Lecture 8 EEB 13 31 January...

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