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DNA%20Mutations%20and%20Repair

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DNA Mutations and Repair Chapter 17 Mutation: is defined as an inherited change in genetic information by cell division or individual organisms. – PowerPoint PPT presentation

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Title: DNA%20Mutations%20and%20Repair


1
DNA Mutations and Repair
  • Chapter 17

2
Mutation is defined as an inherited change in
genetic information by cell division or
individual organisms.
Chernobyl, April 26th, 1986
3
Mutations can be classified into categories.
Categories of mutations
4
Somatic and germ line
5
Achondroplasia
Autosomal Dominant
6
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
7
Gene Mutations can also be classified by type of
mutation
  • Base Substitutions
  • Transitions and Transversions

can be
8
PURINE TO PYRIMIDINE PYRIMIDINE TO PURINE
PURINE TO PURINE
9
Expanding trinucleotide repeats
10
Fragile X Syndrome
Pre-mutation
11
Fragile X syndromeFMR-1 gene
12
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13
Strand slippage may cause repeats
14
Phenotypic changes and mutations
15
Reverse mutation
Forward mutation
16
Forward versus Reverse Mutations
17
Terms associated with PHENOTYPIC effects of
mutations on protein structure
18
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
19
Loss of Function can also occur!
Typically recessive mutations!
20
Suppressor Mutations is a genetic change that
hides the effect of another mutation
21
Intragenic Suppressor Mutations
22
Intergenic Mutation
23
Lethal Mutations
24
Do you remember something about each type of
mutation?
25
This is easy!
26
Mutation Rates and Frequency
1 to 10 mutations per million gametes
Incidence within a group
27
Causes of Mutations
Spontaneous
Induced
28
Environmentally Induced DNA changes
29
Intercalating agents
  • Insert and distort DNA

30
Radiation
(Techa River)
Hiroshima (Aug. 6th, 1945)
31
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32
Thymine Dimers
SOS
33
Chemicals and Reactions Leading to Mutations
34
alklyating
Deamination
Adds OH
35
Oxidative radicals
  • Reactive forms of oxygen can lead to these
    radicals

36
Detecting mutations with the AMES test
37
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38
THE AMES TEST
Salmonella typimurium
39
AMES TEST
  • Saccharin
  • Aflatoxin

2-aminofluorene
40
Aflatoxin B1
41
DNA Repair general characteristics
  • Double stranded DNA
  • Redundancy of pathways

42
Types of DNA repair
  • Mismatch repair
  • Direct Repair
  • Base-Excision Repair
  • Nucleotide Excision Repair

43
Mismatch repair
  • Mut H
  • Recognize GATC hemi-methylation
  • Mut S
  • Mut L

44
A closer look at mismatch repair
45
DIRECT REVERSAL REPAIR
Direct Repair
46
BASE EXCISION REPAIR
47
BASE EXCISION REPAIR
48
Nucleotide Excision Repair
49
Diseases of DNA repair!
50
Xeroderma pigmentosum Autosomal recessive
51
Hereditary Non-Polyposis Colon Cancer
  • HNPCC
  • 15 of all colon cancers

52
Li-Fraumeni
  • P-53 mutation

53
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54
The End
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