LIFESCI 3 Chapter Notes - Chapter 13.1: Holliday Junction, Dna Replication, Homologous Chromosome
Document Summary
Replication continues over the lesion through translesion synthesis. Lesion repair is initiated but not completed. Break in template strand is present when replication fork arrives. Replisome encounters a lesion undergoing ner or ber template may contain temporary break. Replication fork arrives one branch of fork becomes disconnected and fork collapses. Replication machinery can be blocked by lesion but resumes downstream. Lesion is left behind with no undamaged complementary strand present to guide common dna repair pathways. Oxidative dna damage lesion destroy continuity of both template strands double strand break. Replication fork encounters a break in a template strand that is undergoing repair . Recombinational dna repair requires the presence of another undamaged homologous double stranded dna. Second copy of each chromosome or sister chromatid provides template for restoration of genetic info. 5" ending strands degraded to create 3" single stranded extensions/overhangs. Dna strand invasion: 3" overhang invade the homologous chromosome through catalyzation by recombinases.
