BIOL 3315 Chapter 12: CH. 12
Document Summary
12 gene mutation, dna repair, & homologous recombination. A mutation is a heritable change in dna sequence. The ultimate source of genetic variation for evolution. Mutagens agents that increase the rate of mutations. Spontaneous mutations influencing phenotype occur at a very low rate. Variation reflects mutation tolerance, replication efficiency, efficiency of repair mechanisms, and gene structure. Luria and delbruck (1943) tested whether mutations were random with respect to their effects or adaptive mutations occur when the environment changes. Adaptation mutation hypothesis predicts that all populations carry approx. the same proportion of phage-resistant cells. Mutations would also occur only when phage were added. Random mutation hypothesis predicts that the number of phage-resistant cells fluctuates substantially among populations as a result of random timing of mutation. Note: indels can be more than 1 bp in length. The mutant polypeptide contains an altered amino acid sequence from the point of mutation to the end of the polypeptide.
