Chapter 23

Chapter 23 - Biology 1202 1 Mutation and Sexual...

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Biology 1202 – January 23, 2008 1) Mutation and Sexual Reproduction produce the variation that makes evolution possible a) Mutations changes in nucleotide sequence of DNA i) Source of new alleles and genes b) Point mutation: change in one nucleotide base in a gene c) Chromosomal mutations: delete, disrupt, or rearrange many loci on a chromosome d) Gene duplications: duplication of whole segments of a chromosome e) Mutation rate averages 1 in every 100,000 genes per generation 2) Sexual Recombination a) In sexually reproducing organisms, sexual recombination produces most of the variability in each generation 3) Genetic drift and gene flow can alter a population’s genetic composition a) Statistically, the smaller a sample the greater the chance of deviation from a predicted result b) With small population sizes, allele frequencies can fluctuate unpredictably from one generation to the next c) Tends to reduce genetic variation QuickTimeª and a TIFF (Uncompressed) decompressor are needed to see this picture.
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Chapter 23 - Biology 1202 1 Mutation and Sexual...

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