BSC 196 Lecture Notes - Lecture 4: Point Mutation, Sexual Reproduction, Mutation
Document Summary
Variation in heritable traits is a prerequisite for evolution. Natural selection can only act on variation that"s heritable (if a trait is not heritable, it won"t be passed down) Leads to new alleles and new genes. Creates genetic variation by producing novel combinations of existing alleles. Mutation - mistake made during dna copying process. Origin of variation and mechanism of change: point- source of new alleles, chromosomal- source of new genes, species. Point mutation: change in one of the nucleotide bases. Mutations that result in a change of protein are often harmful. Harmful mutations can be hidden from selection in recessive alleles. Mutations that result in change in protein production can sometimes be beneficial. Chromosomal mutations that delete, disrupt or rearrange many loci (position of genes) are typically harmful. Duplication of small pieces of dna can be harmless. Mutation rates are low in animals and plants. The average is about one mutation in every 100,000 genes per generation.
