1. DNA Repair

2. Cell Cycle Checkpoint activation DNA Repair: Base Excision Repair Nucleotide excision repair Mismatch repair DSB repair SENESCENCE / APOPTOSIS CANCER

3. Source of Damage  Endogenous:  Replication Errors  Reactive Oxygen Species  Exogenous:  UV radiation, IR..  Mutagenic chemicals

4. Type of Damage- Endogenous  Oxidation of bases  Methylation of bases  Hydrolysis of bases  Mismatch of bases Damage mostly on DNA bases, causing point mutations:

5. Type of Damage- Exogenous  UV light- pyrimidine dimers  IR- Breaks in DNA strands  Chemicals (found in smoke, soot and tar)- diversity of DNA damages including crosslinking of DNA. Damage mostly on helix structure:

7. DNA MutationDNA Damage ≠

8. The cellular DNA damage response Transducers Mediators Sensors Effectors Cell cycle arrest DNA repairApoptosisDNA repair DNA damage

9. DNA Repair Mechanisms

10. DNA Mismatch repair

14. Base Excision Repair

15. Nucleotide excision repair

16. Nucleotide Excision Repair in Eukaryotes

17. Xeroderma Pigmentosum