Post on 22-Dec-2015
Microbial Genetics (Micr340)
Lecture 14DNA 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
Specific Repair Pathways
Repair of deaminated bases Damage due to reactive oxygen Alkylation of DNA and repair Pyrimidine dimer repair
Base Deamination by nitrous acid
Spontaneous Base Deamination
Repair of altered bases by DNA glycosylases
Damage due to reactive oxygen
Mechanism of avoiding GO
AlkylationOf guanine
Repair of alkylated DNA
Specific N-glycosylases Methyltransferases
PyrimidineDimer Formation
Photoreactivation
General Repair Mechanisms
Methyl-directed mismatch repair system
Nucleotide excision repair SOS inducible repair
A model for methyl
Directed mismatch
repair
A model for nucleotide excision repair
SOS response
SOS response
Regulation of SOS mutagenesis in E. coli