1. Maintenance of genomes Correcting replication errors Repairing DNA damage

2. Maintenance of genomes Replication errors Inserting a wrong nucleotide causing a mismatch Inserting or deleting nucleotides causing helix distortion

3. Figure 16.3b Genomes 3 (© Garland Science 2007)

4. Figure 16.4 Genomes 3 (© Garland Science 2007)

5. An error in replication can cause a point mutation

6. Maintenance of genomes Replication errors Inserting a wrong nucleotide causing a mismatch Inserting or deleting nucleotides causing helix distortion

7. Figure 16.5 Genomes 3 (© Garland Science 2007) Replication slippage in microsatellites

8. Table 16.1 Genomes 3 (© Garland Science 2007)

9. Mismatch repair in E. coli

11. Maintenance of genomes DNA damage Physical damage – radiation, heat Hydrolytic damage Chemical damage – base modifications, base analogs, intercalating agents

12. Crosslinks caused by UV light

13. Figure 16.9 Genomes 3 (© Garland Science 2007) Cyclobutyl dimers and formation of a (6-4) photoproduct caused by UV light (results in a deletion)

14. In some organisms photolyases repair crosslinks In humans the damaged region is excised and re-synthesized

15. Maintenance of genomes DNA damage Physical damage – radiation, heat Hydrolytic damage Chemical damage – base modifications, base analogs, intercalating agents

16. Hydrolytic damage to bases

17. Maintenance of genomes DNA damage Physical damage – radiation, heat Hydrolytic damage Chemical damage – base modifications, base analogs, intercalating agents

18. Base analogs and intercalating agents can cause point mutations and insertions/deletions

19. Figure 16.6c Genomes 3 (© Garland Science 2007)

20. Various damages to bases

21. Direct repair of methylated bases

22. Figure 16.22a Genomes 3 (© Garland Science 2007) Base excision repair

23. Base excision repair (removal of uracil)

24. Fail-safe glycosylases

25. Table 16.3 Genomes 3 (© Garland Science 2007)

26. Nucleotide excision repair in E. coli Short patch repair

27. Transcription-linked repair

28. Double-strand break repair (Non-homologous end joining) Double-strand breaks are caused by ionizing radiation

29. Figure 16.20 Genomes 3 (© Garland Science 2007) DNA repair processes

31. Replication-linked repair SOS repair in E. coli Expression of Pol IV and Pol V is induced by DNA damage.

32. Switching to translesion DNA polymerases

33. Figure 16.11 Genomes 3 (© Garland Science 2007) Effect of mutations on gene expression