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Microbial Genetics (Micr340)

Microbial Genetics (Micr340) . Lecture 14 DNA Repair and Mutagenesis. Definitions. Lesion: chemical damage in DNA Mutagens: chemical compounds that cause lesions in DNA which can kill cells and can also increase frequency of mutations in DNA. Evidence for DNA repair.

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Microbial Genetics (Micr340)

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  1. Microbial Genetics (Micr340) Lecture 14 DNA Repair and Mutagenesis

  2. Definitions • Lesion: chemical damage in DNA • Mutagens: chemical compounds that cause lesions in DNA which can kill cells and can also increase frequency of mutations in DNA

  3. Evidence for DNA repair

  4. Specific Repair Pathways • Repair of deaminated bases • Damage due to reactive oxygen • Alkylation of DNA and repair • Pyrimidine dimer repair

  5. Base Deamination by nitrous acid

  6. Spontaneous Base Deamination

  7. Repair of altered bases by DNA glycosylases

  8. Damage due to reactive oxygen

  9. Mechanism of avoiding GO

  10. AlkylationOf guanine

  11. Repair of alkylated DNA • Specific N-glycosylases • Methyltransferases

  12. PyrimidineDimer Formation

  13. Photoreactivation

  14. General Repair Mechanisms • Methyl-directed mismatch repair system • Nucleotide excision repair • SOS inducible repair

  15. A model for methylDirected mismatch repair

  16. A model for nucleotide excision repair

  17. SOS response

  18. SOS response

  19. Regulation of SOS mutagenesis in E. coli

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