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Lecture 8
N/A
18
Biology
Undergraduate 2
10/03/2011

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Term
DNA polymerase
Definition
Needs a primer. Work 5'-3'.
Term
Semiconservative DNA replication
Definition
One new strand runs 5'-3', the other runs 3'-5'.
Term
Synthesis of leadings and laggings.
Definition
Leading is synthesized 5'-3' (up, here). The lagging strand would be 3'-5' if it was made going up so it's actually synth'ed using Okazaki fragments (1-3 kb)
Term
Okazaki primer
Definition
Made of RNA - can start from scratch. From the RNA primer, DNA polymerase extends and makes the Okazaki fragment 5'-3' (here it's down).
Term
Removal of RNA primers, joining of Okazaki
Definition
RNase H removes the primer, DNA fills the gap, DNA ligase seals the new Okazaki with the preceding Okazaki.
Term
DNA polymerases
Definition
E. coli - leading strand = pol III, lagging strand = Primase, pol III.
Mammals - leading strand = pol epsilon, lagging strand = pol alpha/primase complex, pol delta.
Term
Polymerase accessory proteins
Definition
Clamp-loading protein (RPC) and Sliding Clamp (PCNA) load polymerase on end of primers and keeps it associated w/ template.
Term
E. coli replicates how fast?
Definition
100,000 bases/min
Term
Helicases and ssDNA-binding proteins
Definition
Helicase unwinds, proteins bind to ssDNAs and keep them from reassociating.
Term
Topoisomerases
Definition
Cut either one or both strands temporarily to let DNA swivel during replication, preventing a coiled mess.
Term
Model of E. coli replication.
Definition
Figure 6.10
Term
Error rate of DNA replication
Definition
<1 error per 10^9
Term
Error reducing factors
Definition
H bonding: favors correct base pairing by 1 error per 10^2
Base selection by DNA pol: becomes 1 per 10^5.
DNA polymerase proofreading: becomes 1 per 10^7 or 10^8.
Mismatch repair: becomes <1 per 10^9
Term
DNA pol proofreading
Definition
Wrong base won't bond smoothly, pol will backtrack and remove the wrong base using 3'-5' exonuclease, then continue.
Term
Origins of replication
Definition
245 bp area where initiator protein binds, RNA primers synth, helicase and ssDNA-binding proteins go to work, and replication starts happening from two ends creating a "bubble" of daughter strands. E. coli = 1 ori, humans = 1 ori per 50-100 kb.
Term
Eukaryotic oris
Definition
Start at points along strand and replicate from two ends until the bubbles join and the new strands completely split.
Term
ID of oris in yeast
Definition
Transform different sequences into plasmids, if the resulting cells can replicate with just the supplied sequence this shows that the sequence could replicate and is an ori.
Term
Ori structure
Definition
Oris are not defined when comparing sequences of eukaryotes so it's thought that the chromatin structure determines where an ori is (like how histones are dependent on chromatin). Epigenetic inheritance.
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