GEN-3000 Chapter Notes - Chapter 14: Pyrimidine Dimer, Dna Mismatch Repair, Dna Ligase
15 Nov 2017
School
Department
Course
Professor
Document Summary
Evolved variety of systems to counteract spontaneous and induced damage. This system responds after damaged dna has failed to be replicated and has escaped repair. A lesion has formed in the dna (ex. During replication polymerase: a) stalls at the lesion or b) skips over it which leaves an unreplicated gap. Use homologous recombination repair with the corresponding strand. The gap is filled by dna polymerase and dna ligase. Sos repair system and photoreactivation repair (only in e. coli) Sos repair system: acts in presence of large number of unrepaired dna mismatches and gaps. Overrides the command to stop replication and goes forth with it even in the face of largescale dna damage. Photoreactivation repair: reverses damage done by uv light. Damage = reversed when exposed to blue light. Photoreactivation enzyme = goes into dna and cleave covalent bonds bonds. This occurs when errors are found after the replication process concludes. Final checkpoint to make sure everything is in order.
