Micro/Genome 411 Lecture 7 DNA REPAIR I. Induced mutations A. Chemical mutagenesis 1. Base-modifying agents 2. Base analogs B. Physical mutagenesis ? uv irradiation II. Dealing with DNA lesions A. Repair mechanisms 1. Light-mediated repair (photoreactivation) 2. Excision repair B. Bypass mechanisms 1. Replicative repair 2. Recombinational repair 3. Error-prone repair III. The SOS response A. Regulation B. Scope and significance of the response Lecture 7: DNA Repair Micro/Genome 411 Lecture 7: DNA Repair Micro/Genome 411 DNA polymerases in E. coli: DNA pol I:DNA repair; RNA primer removal DNA pol II:??? (DNA repair?) DNA pol III:Chromosome replication; mismatch repair DNA pol IV:(DinB) Error-prone repair DNA pol V:(UmuCD) Error-prone replication DNA pol IV and pol V lack proofreading function & are able to bypass ("read through") lesions. Genes repressed by LexA: ?Excision repair genes (uvrABC) Error-prone repair genes (umuCD, dinB) ?Cell division inhibitor (sulA) SOS regulatory genes (recA, lexA) Lecture 7: DNA Repair Micro/Genome 411 UV exposure C e l n u m b e r UV exposure % m u t a n t s Kendall Gray Microsoft Word - Lecture 7 handout.doc
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