DNA Mutations and Repair Chapter 17 Part 1

Gene Mutations and Repair Nature of mutations Causes of mutations Study of mutations DNA repair

Nature of Mutations Chernobyl, April 26th, 1986

Mutation: is defined as an inherited change in genetic information by cell division or individual organisms.

Mutations can be classified into categories. Categories of mutations

Somatic and germ line

Achondroplasia Autosomal Dominant

Gene Mutations can also be classified by type of mutation 1. Base Substitutions □ 2. Insertions and deletions 3. Frameshift mutations 4. Expanding trinuleotide repeats Lead to

Gene Mutations can also be classified by type of mutation Base Substitutions Transitions and Transversions can be

PURINE TO PYRIMIDINE PYRIMIDINE TO PURINE PURINE TO PURINE

Expanding trinucleotide repeats

Fragile X Syndrome Pre-mutation

Fragile X syndrome:FMR-1 gene

Strand slippage may cause repeats

Spontaneous: slippage

Phenotypic changes and mutations

Reverse mutation Forward mutation

Forward versus Reverse Mutations

Terms associated with PHENOTYPIC effects of mutations on protein structure Can be “neutral” redundancy

Phenotypic effects can also change function Gain of Gene Function1 Loss of Gene Function2 1 Sullivan, J.P. et al., Department of Pathology, College of Veterinary Medicine, 1998 The University of Georgia, Athens, GA or Qualtek Molecularlabs Web Site

Loss of Function can also occur! Typically recessive mutations!

Suppressor Mutations is a genetic change that hides the effect of another mutation

Intragenic Suppressor Mutations

Intergenic Mutation

Lethal Mutations

Do you remember something about each type of mutation?