LIFESCI 3 Lecture Notes - Lecture 13: Dna Mismatch Repair, Nonsense Mutation, Tautomer
Document Summary
Mutability and repair of dna: dna damage is inevitable --> has major consequences to cell if not repaired, multiple sources of mutations or damage to dna: Inaccuracy in dna replication: spontaneous change, exogenous damage: radiation, chemicals, certain chemical by-products of normal cellular metabolism, 2 major consequences of dna damage, mutations (esp in gene or its regulatory sequences) Dna polymerase has proofreading 3"-->5" exonuclease activity: destabilizes primer:template junction, decreases the error rate of dna replication by factor of ~100, mismatch repair (e. coli, 2nd chance to repair rep errors that escaped proofreading, 2 challenges, 1. ) Mismatches are transient after 2nd round of rep, the mismatch is eliminated and leads to a mutation that won"t be detected: 2. ) Specifically repair the daughter strand not parent strand: process: mismatch repair machinery: muts, mutl, muth, muts (dimer)--scans the dna & detects mismatches based on distortion to dna structure.
