Biology 1001A Chapter Notes - Chapter 12: Euchromatin, Heterochromatin, Histone H2B
17 Dec 2017
School
Department
Course
Document Summary
Proofreading mechanism ability for dna pol to back up and remove mispaired nucleotides then continue to add. The dna polymerase reverses uses a built in deoxyribonuclease using a 3" to 5" exonuclease to remove the misparied base from strand and adds the right one. Then it continues building in the forward direction extending in 3" to 5" direction. Mismatch repair - increases accuracy of dna replication , after proofreading, the bas mismatches distory the structure of the dna helix and these distortions provide reconizition sites for enzymes catalyzing mismatch repair o. Distortions could be because: wrong base, chemicals, radiation (ultraviolet) The repair enzymes move along double helix scanning the dna , if theres a distortion they remove a portion of the new chain (breaking backbone of new strand) including mismatched nucliotides. The gap is filled by a dna polymerase using the template strand as a guide.
