BIOSC-101 Chapter Notes - Chapter 1: Histone H1, Nucleosome, Proofreading
31 Aug 2020
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Document Summary
Dna polymerases make very few errors, but the few mistakes that do occur are bp mismatches, which are corrected by either. Proofreading mechanisms where the polymerases back up and remove the mispaired nucleotides from the complementary strand complementary to the template strand. Synthesis only occurs when the most recently added base is. If there is a mistake, the polymerase uses its 3"-5" exonuclease activity to remove the mispaired nucleotide, fixes it, and moves on. Any bp mismatches that remain after proof-reading face correction by dna repair mechanisms. Correct bp matches fit the 0. 34 nm dimensions, so mispaired bases are too large or small to main separation. Bp mismatches distort dna structure, and provide recognition sizes for the repair enzymes. The enzymes look for the mistake, and remove it, and polymerase fills up the gap, and ligase seals it up. The same repair mechanisms fix the effects of radiation.
