Week 10: Cell Replication and PCR

University:
The Pennsylvania State University
Course:
BIOL 230W | Cellular Biology
Academic year:

2023
Views:

368

Pages:

2
Author:

Sarah Landeck

BIOL 230W - Week 10 Cell Replication and PCR — During replication, chromosomes need to be euchromatic (loosely packed) — Origins are speci c regions of DNA that get recognized (proteins bind to these origins and initiate replication - Origin Recognition Complex) —> ORCs preferentially bind to AT regions = easier to separate than GC —> After ORC binds, CDT1 and CDC6 form helicase loader to recruit helicase — * g. 2 from slides — Pre-replication complex is made of ORC, helicase loader, and helicase — MCM-double helicase cleaves 2 strands of DNA (placed in G1, active in S) — Geminin: protein that blocks addition of helicase (prevents loading into PRC) Cell Replication and PCR pt 2 — Replisome: contains all the proteins required from DNA replication — Components = helicase, topoisomerase, DNA binding proteins, DNA polymerase, sliding clamp — The leading strand is continuously polymerized (one primer) and the lagging strand gets polymerized in pieces (lots of primers) — Processivity: amount of times enzyme can add nucleotides before falling o —> Clamp proteins increase processivity, keep polymerase in contact w DNA — In the nal step of replication, DNA ligase forms phosphodiester bond Cell Replication and PCR pt 3 — PCR ampli es a section of DNA by cycling 3 steps (denature, anneal, extend) —> Denaturation is done by heating DNA to 96 degrees ff fi fi fi fi —> Annealing uses DNA primer to provide 3’ end (form H bonds w region) —> During extension, moves 5’ to 3’ end using enzymes (to extend molecule) — During every PCR cycle, the amount of DNA doubles (exponential growth) — Melting temperature of DNA is when half H-bonds are broken (half SS)