Transcript ch. 17 DNA mutations and repair

DNA Mutations and Repair
Chapter 17
pp. 481-
Mutation Rates and Frequency
1 to 10 mutations per million gametes
Incidence within a group
For example: swine flu incidence in the U.S
Causes of Mutations
Spontaneous
Induced
Environmentally Induced DNA changes
Intercalating agents

Insert and distort DNA
Radiation
Hiroshima (Aug. 6th, 1945)
(Techa River)
Thymine Dimers
SOS
Chemicals and Reactions Leading to Mutations
alklyating
Deamination
Adds OH
Oxidative radicals

Reactive forms of
oxygen can lead to
these radicals
Detecting mutations with the AMES test
THE AMES TEST Salmonella typimurium
AMES TEST
2-aminofluorene

Saccharin

Aflatoxin
Aflatoxin B1
DNA Repair: general characteristics


Double stranded DNA
Redundancy of pathways
Types of DNA repair

Mismatch repair

Direct Repair

Base-Excision Repair

Nucleotide Excision Repair
Mismatch repair

Mut H



Recognize GATC hemi-methylation
Mut S
Mut L
A closer look at mismatch repair
DIRECT REVERSAL REPAIR
Direct Repair
BASE EXCISION REPAIR
BASE EXCISION REPAIR
Nucleotide Excision Repair
Diseases of DNA repair!
Xeroderma pigmentosum
Autosomal recessive
Hereditary Non-Polyposis Colon Cancer

HNPCC

15% of all colon
cancers
Li-Fraumeni

P-53 mutation
The End