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12-4 Mutations. Mutation = change in genetic material Gene mutation = changes in a single gene Chromosomal mutation = changes in whole chromosomes. Gene Mutations. Point Mutations = Changes in one or a few nucleotides Include: substitutions, insertions, and deletions.
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Mutation = change in genetic material • Gene mutation = changes in a single gene • Chromosomal mutation = changes in whole chromosomes
Gene Mutations • Point Mutations = Changes in one or a few nucleotides • Include: substitutions, insertions, and deletions
Types of Point Mutations • Substitutions = one base is changed to another • Usually affects a single amino acid • Insertions = one base is inserted • Deletions = one base is deleted • More dramatic changes • Cause frameshift mutations • Changes all amino acids after the point of change
Chromosomal Mutations • Changes in the number or structure of chromosomes • May even change the number of copes of some genes
4 Types of Chromosomal Mutations • Deletions = loss of all or part of a chromosome • Duplications = extra copies of parts of a chromosomes • Inversions = reverse direction of parts of a chromosomes • Translocations = part of one chromosome breaks off and attaches to another
Significance of Mutations • Most have little effect • Dramatic changes = usually harmful • Producing defective proteins that don’t do their job • Mutations = source of genetic variability! • Can be very good! Useful!