DNA Mutations and Repair

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DNA Mutations and Repair

• Chapter 17
• Part 1

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Gene Mutations and Repair

• Nature of mutations
• Causes of mutations
• Study of mutations
• DNA repair

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Nature of Mutations
Chernobyl, April 26th, 1986
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Mutation is defined as an inherited change in
genetic information by cell division or
individual organisms.
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Mutations can be classified into categories.
Categories of mutations
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Somatic and germ line
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Achondroplasia
Autosomal Dominant
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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
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Gene Mutations can also be classified by type of
mutation

• Base Substitutions
• Transitions and Transversions

can be
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PURINE TO PYRIMIDINEPYRIMIDINE TO PURINE
PURINE TO PURINE
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Expanding trinucleotide repeats
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Fragile X Syndrome
Pre-mutation
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Fragile X syndromeFMR-1 gene
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Strand slippage may cause repeats
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Spontaneous slippage
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Phenotypic changes and mutations
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Reverse mutation
Forward mutation
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Forward versus Reverse Mutations
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Terms associated with PHENOTYPIC effects of
mutations on protein structure
Can be neutral
redundancy
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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
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Loss of Function can also occur!
Typically recessive mutations!
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Suppressor Mutations is a genetic change that
hides the effect of another mutation
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Intragenic Suppressor Mutations
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Intergenic Mutation
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Lethal Mutations
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Do you remember something about each type of
mutation?
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