Biochemistry 2280A Lecture Notes - Lecture 30: Homologous Recombination, Chromosome, Xeroderma Pigmentosum
Document Summary
Dna repair systems (corresponds to the type of error: proofreading during dna replication, mismatch repair: fix mistakes made by dna polymerase, looks for mistakes on the newly synthesize strand and fixes them. Involves potentially re-synthesizing long stretches of dna: mismatch repair for eukaryotes. The newly synthesize strand is the top, red strand. Turns out that there"s nicks left in the newly synthesized strand. When you come across a mismatch (example/ a and g together), there"s no way to tell which one is the wrong one because both a and g belong in the genome. Remove the damaged base, if necessary (not damaging the backbone, just taking out the base) (if necessary, because in abasic sites, this has already happened) Repair dna polymerase adds 1 (short patch) or 2-10 (long patch) new nucleotides. Excess dna is trimmed from the damaged strand.