DNA Replication Flashcards
What is DNA replication (conservative or semi conservative)? What bonds does it produce?
Semi Conservative (1 parental 1 new strand), 1 light density bond and 1 faint density hybrid bond
Theta
bacteria (circular dna) - bidirectional, replication bubble
Rolling Circle
virus, unidirectional
Linear
eukaryotes, bidirectionally, replication bubble, 2 points of origin
What does replication require?
Dna poly, 4dNTPs (dna synthesised), template strand, RNA primer (3’OH strand attacks 5’P group of incoming dNTP to initiate DNA synthesis by DNA poly in 5’-3’ direction)
Prok replication - What opens up DNA?
What unwinds in 5-3 prime direction?
What do binding proteins do?
What does gyrase do?
What does topoisomerase do?
What does Primase do?
DnaA opens up DNA (binds to OriC), helicase unwinds in 5-3 direction by disrupting H bonds, binding proteins keep Dna ss and prevents hairpins from forming, gyrase prevents torsion, topoisomerase makes double stranded breaks in DNA to relieve strain, primase makes primers.
Prok polly 3
elongates 5-3 polymerase, 3-5 exonuclease (good for moving back and editing)
Prok polly 1
removes primers, 5-3 and 3-5 exonuclease activity, lacks B clamp so not good for elongating
How polly works on lagging strand
Polly 3 reaches 5’ end of primer, polly 1 comes on 5’-3’ exonuclease activity to remove primers, ligase makes phosphodiester bonds between 5’P group and 3’OH group and okazaki fragments are joined.
Eukaryotic replication - Where does it being?
What does helicase do?
What is the compex called?
What effects stability and packaging?
How many histones?
What do telomeres do?
begins at an AT rich area, helicase binds to initiator on double stranded DNA (MCM complex), nucleosomes effect stability and packaging, 2 histones, and telomeres shorten after each round
