DNA Mutations and RepairChapter 17Part 1

Gene Mutations and Repair Nature of mutations

Causes of mutations

Study of mutations

DNA repair

Chernobyl, April 26th, 1986

Nature of Mutations

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 PURINEPURINE TO PYRIMIDINE

PYRIMIDINE 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 mutationForward mutation

Forward versus Reverse Mutations

Terms associated with PHENOTYPIC effects of mutations on protein structure

redundancyCan be “neutral”

Phenotypic effects can also change function

1 Sullivan, J.P. et al., Department of Pathology, College of Veterinary Medicine, 1998 The University of Georgia, Athens, GA

Gain of Gene Function1

Loss of Gene Function2

Qualtek Molecularlabs Web Site

or

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?