Biology 1001A Lecture Notes - Lecture 6: Genome Size, Copy-Number Variation, Human Genome Project
25 Apr 2017
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Lecture 6- origin of variation sept. 29/2016: mechanism of proofreading. Dna polymerase backs up and removes mispaired nucleotides from a newly synthesized dna strand. Only after the most recently paired base is correct can the dna polymerase continue to add nucleotides and elongate the chain: mechanism of mismatch repair. Dna reverses using 3" 5" exonuclease to remove the incorrect nucleotide. Exonuclease essentially chops off the mutant strand and then dna polymerase comes by to synthesize the correct nucleotide. Double stranded breaks during g1 (nhej: general trends in costs of dna sequencing. Costs are dropping every year: relative distribution of various components of genome sequence (junk vs. essential dna) 10% essential (2% for coding) (other 8% are things eg. telomeres) 25% unknown (likely junk: proportion of human genome coding for protein. 2: difference between dna damage and mutation. If the dna replication error is a double stranded change, it is a mutation.
