MBIO 2020 Lecture Notes - Lecture 3: Type Ii Topoisomerase, Dna Gyrase, Dna Ligase
25 Nov 2017
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Lagging strand: dna polymerase iii synthesizes okazaki fragments but stops when encountering preceding rna primer leaving a gap, dna polymerase i recognizes gap and initiates synthesis from 3" oh in a 5". 2- using atp as energy: note that dna polymerase can only extend from 3"-oh but cannot catalyze a phosphodiester linkage with a 5"- po4. Ssb (single strand binding proteins)- prevent reformation of double helix the sub complex primosome includes the helicase and primase: unwind and prime the dna, dna is moved through the complex rather than dna polymerase moving on the. Dna: positive supercoils when you open the replication bubble, and if you unwind. 2: helicase + primase = helisome, the b-clamp secures dna polymerase iii to the strand, the b- clamp is the smaller half donut looking thing attached to the larger bitten donut looking thing (dna polymerase iii)
