BIO130H1 Midterm: midterm pt2
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BIO130H1 Full Course Notes
Verified Note
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Document Summary
Problem: ends of dna (telomerase, shortening of dna in lagging strand-> lose info, winding problem (topoisomerase, mistakes (exonuclease) (263-288) Low mutation rates are necessary for life as we know it. Unwinds dna after initiation protein (replication bubble, replication fork) Helicase- predominant = 5" 3": 6 identical subunits, each bind atp (being hydrolyzed, single stranded binding proteins (binds to single-stranded dna & prevent single-strands from reforming base pairs; stabilize unwound, single-stranded conformation of dna) Place holders: dna primase, dna ligase. One strand in daughter molecule is conserved from parental molecule. & other is newly synthesized; bi-directional from 5" 3" (not conservative: both strands conserved -> daughter consist 2 newly synthesized strands) High fidelity of dna replication requires several proofreading mechanisms: rna 1/100000, dna 1/10000000000, 3" -> 5" exonuclease activity (part of dna polymerase) Immediately after incorrect nucleotide is covalently added to growing chain.
