Mutations Chapter 12.4

Mutation A result of changes in individual genes or the gene arrangements on chromosomes Original code (order of bases) is changed 2 different kinds Gene mutation Chromosome mutation

Gene Mutations Mutations occurring within a gene Usually a letter change, removal, or addition Three different types: Deletion Insertion Point mutation

Gene deletions and insertions Gene deletion  nucleotide is left out Gene insertion  an extra nucleotide is added These are called frame-shift mutations causes the order of bases to switch, which causes change in codons, which in turn changes amino acid sequence

Point mutations Point mutation  a base is substituted for one other base Will only affect one amino acid in the protein

Point Mutation - Deletion

Chromosome Mutations Mutations that occur within a chromosome or between chromosomes 4 different types: Deletions Duplications Inversions Translocations

Deletions and Duplications Chromosomal deletion  part of a chromosome are removed Chromosomal duplication  part of a chromosome is duplicated

Inversion and Translocation Chromosomal inversion  portion of a chromosome is reversed Chromosomal translocation  part of one chromosome attaches to another, different chromosome

Mutagens Mutagen an agent that causes a mutation environmental factors such as radiation, heat, and chemicals

Passing On of Mutations Mutations that occur in “body cells” do not get passed on to offspring Mutations that occur in “sex cells” do get passed on to offspring

Mutation and Evolution Mutations could cause a new allele for a characteristic Mutations could also be the fuel that drives evolution individuals that underwent mutations may be better suited for survival than the original