Biology 1001A Study Guide - Midterm Guide: Genetic Drift, Sickle-Cell Disease, White Feathers
31 Jan 2017
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Document Summary
Replication isn"t perfect and sometimes polymerase will put in the wrong base. Dna polymerase 3 will break the dna strand and x the base-pairing, base-pair mismatch will be corrected by proofreading (dna polymerase will back up and remove miscarried nucleotides from new dna strands. In order for polymerase to add nucleotides, the bases must be paired correctly and if a mismatch is added, the polymerase will reverse this using a built in deoxyribose to remove the incorrect nucleotide. Dna repair mechanisms: sometimes, base-pairs escape proofreading, therefore other mechanisms must be used *** need the a-t g-c match because of the dimensions separating sugar-phosphate backbone chains requires a constant distance to be hydrogen stabilized. Mismatches distort the structure and therefore act as recognition sites for enzymes, catalyzing mismatch-repair enzymes scan for distortions and when encountered they will remove the mismatched portion and ll the gap with. Dna polymerase, with dna ligase sealing the chain.
