BIOL 230W Lecture Notes - Lecture 22: Topoisomerase, Alpha Helix, Primase
Document Summary
Biol 230w lecture 22 replication fork. Prokaryotes: primase synthesizes rna primers, pol i replaces rna primers, pol ii finishes. Eukaryotes: primase activity completed by dna pol alpha, leading and lagging strand replication by dna pol delta, dna pol epsilon repairs errors introduced by dna pol delta. Processivity: number of catalytic cycles an enzyme maintains while associated with the substrate. Positively charged alpha helices: attracted to negatively charged dna. Dna polymerase requires 3" end to function. Primer removal: add back dna, cause gaps between backbone, must ligate (ligase) Helicase, topoisomerase, opc required to start the replication process. Helicases break hydrogen bonds so replication machinery can access each template strand. Single stranded binding proteins keep template strands separated as dna polymerase replicates dna. Nucleotides added to 3" end of existing strand. Primases add short stretch of rna (primer) Initial strand for dna polymerase to elongate: later removed by polymerase, replaced by dna.
