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DNA Mutations and Repair. Chapter 18 Part 1. Gene Mutations and Repair. Nature of mutations Causes of mutations Study of mutations DNA repair. Source of Mutations. Nuclear accidents. Chernobyl, April 26 th , 1986. Source of Mutations. - PowerPoint PPT Presentation
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DNA Mutations and RepairChapter 18Part 1
Gene Mutations and Repair Nature of mutations
Causes of mutations
Study of mutations
DNA repair
Chernobyl, April 26th, 1986
Source of Mutations
Nuclear accidents
Source of Mutations
Japan’s Tsunami disabled reactors at the Fukushima Plant March 11, 2001
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
Update on diagnosis of fragile X Syndrome:
Fragile X syndrome was originally diagnosed by culturing cells in a folate deficient medium and then assessing the cultures for X-chromosome breakage by cytogenetic analysis of the long arm of the X-chromosome. This technique proved unreliable for both diagnosis and carrier testing.
The fragile X abnormality is now directly determined by analysis of the number of CGG repeats and their methylation status using: restriction endonuclease digestion and Southern blot analysis.
Strand slippage may cause repeats
Phenotypic changes and mutations
Spontaneous: slippage
Reverse mutationForward mutation
Forward versus Reverse Mutations
Terms associated with PHENOTYPIC effects of mutations on protein structure
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?