BIO 1140 Lecture Notes - Lecture 19: Dna Repair, Dna Ligase, Dna Replication
28 Mar 2017
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Document Summary
Usually is adding new nucleotides in the 5"-3" direction using complementary base pairing rules. Rarely dna poly will add a mis red nucleotides. Dna poly will recognize the mismatches base pair. The enzyme reverses using its 3" - 5" exonuclease to remove mis red nucleotides from the strand. Will resume its polymerization activity in the forward direction. Repair enzymes move along the dna scanning for distortions in the double helix due to a mis red base. The enzymes breathe backbone of the new strand of the strand on each side of the mismatch. Remove several too many bases including the mismatch leaving a gap in the. Dna polymerase re ll the sap using the template strand as a guide. Dna ligase seals the nick left after the repair. Prokaryotes use dna poly i and ii. Eukaryotes use dna poly beta and gamma. No, because either side of the excised portion of the dna is double stranded.
