1. DNA Mutations and Repair
Chapter 17

2. Mutation Rates and Frequency
1 to 10 mutations per million gametes
Incidence within a group

3. Causes of Mutations
Spontaneous
Induced

4. Environmentally Induced DNA changes

5. Intercalating agents
Insert and distort DNA

6. Radiation
(Techa River)
Hiroshima (Aug. 6th, 1945)

8. Thymine Dimers
SOS

9. Chemicals and Reactions Leading to Mutations

10. alklyating
Deamination
Adds OH

11. Oxidative radicals
Reactive forms of oxygen can lead to these radicals

12. Detecting mutations with the AMES test

14. THE AMES TEST
Salmonella typimurium

15. AMES TEST
Saccharin
Aflatoxin
2-aminofluorene

16. Aflatoxin B1

17. DNA Repair: general characteristics
Double stranded DNA
Redundancy of pathways

18. Types of DNA repair Mismatch repair Direct Repair Base-Excision Repair
Nucleotide Excision Repair

19. Mismatch repair
Mut H
Recognize GATC hemi-methylation
Mut S
Mut L

20. A closer look at mismatch repair

21. DIRECT REVERSAL REPAIR
Direct Repair

22. BASE EXCISION REPAIR

23. BASE EXCISION REPAIR

24. Nucleotide Excision Repair

25. Diseases of DNA repair!

26. Xeroderma pigmentosum
Autosomal recessive

27. Hereditary Non-Polyposis Colon Cancer
HNPCC
15% of all colon cancers

28. Li-Fraumeni
P-53 mutation

30. The End