BICD 100 Lecture Notes - Lecture 5: Dna Ligase, Proofreading, Base Pair
6 Oct 2016
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Williams syndrome: when people are too friendly; hypersensitive hearing; musical talent; complete lack of social inhibition: 25 base pair deletions in 25,000 base pair sequence in chromosome. Dna repair when dna is damaged: 1. Proofreading: dna polymerase main job to add nucleotide to3" end of dna strand. Some dna polymerase have ability to recognize incorrect nucleotides from the incorrect shape and wrong h-bonding, cut off wrong one, and continue replication. General dna repair of single strand damage/mutation after proofreading: mistake recognized because of wrong double helical structure, damaged part cut out and gap filled with dna polymerase and connected with dna ligase. Incorrect base is recognized in daughter strand: mutated dna strand is removed, gap repaired by dna polymerase and dna ligase. Difference between parent and daughter dna strand: age. Base excision repair (replaces a chemically changed base) Endonucleases remove deoxyribose phosphate: gap filled with correct base by dna polymerase and ligase.
