Biology 2581B Chapter Notes - Chapter 6: Deamination, Nitrogenous Base, Dna Replication

• School: Western University
• Department: Biology
• Course: Biology 2581B
• Professor: David R Smith

Document Summary

Lecture 7 textbook reading understanding mutations (501) Mutations are heritable changes in base sequence that affect phenotype. Gene is a specific protein-coding segment of dna in a discrete region of a chromosome. Genes are divisible and each gene"s subunits can mutate independently and recombine with each other. Mutations are heritable changes in dna base sequences. Forward mutation: changes a wild-type allele of a gene to a different allele. Reverse mutation: novel mutant allele reverts back to wild type. Mutations may be classified by how they change. Transition: purine replaces purine to pyrimidine replaces pyrimidine. Inversion: 180 degree rotation of a segment and a reciprocal translocation in which parts of two nonhomolgous chromosomes change places. Only a small fraction of the mutations in a genome actually alter the nucleotide sequences of genes in a way that affect gene function. 0. 04 -0. 24 mutations per haploid genome = 1 mutation every 6-30 human gametes.