Symes DNA Replication Flashcards
OriC
Replication initiation region in prokaryotes
- 3 AT-rich sequences
- 4 9bp sites (DNAa binding domain)
DNAa
Initiatior proteins which binds causing the DNA to bend
- splits DNA apart
- binding mediated by positive histone-like proteins
- prokaryotic
DnaB/C
Helicase which displaces DNAa
- prokaryotic
SSBs
Stabilise ssDNA
- prokaryotic
DnaG
Part of the primosome, makes primers
- prokaryotic
Function of DNA Pol 1
Performs primer excision and DNA repair
- fills in gap left behind by primer
- prokaryotic
What does the 3’ exonuclease of DNA Pol 1 do?
Proofreading, removes wrong base
- prokaryotic
Function of 5’ exonuclease of DNA Pol 1
Removes primers (nick translation)
- prokaryotic
Nick Translation
5’ exonuclease removes primer one base at a time until it reaches DNA
- DNA Pol 1 fills in the gap
- DNA ligase then seals the gap
DNA Pol III
Performs the bulk of replication in prokaryotes
- high processivity and high rate
- prokaryotic
Subunits in core enzyme of DNA Pol III
Dimer of alpha, epsilon (3’ exo), theta
- prokaryotic
beta sliding clamp
Part of DNA Pol III
- improves processivity
- negative amino acids on the interior
- prokaryotic
Gamma complex
beta clamp loader
- chi subunit helps DNA Pol III transition form making RNA primer to making DNA
Replisome
Creation of a loop at the replication fork so DNA Pol III can go in the same direction on both strands
What perfroms proofreading in prokaryotes
Epsilon subunit of DNA Pol III removes the mismatched base with its 3’ to 5’ exonuclease
How does termination in prokaryotes occur?
ter and TUS proteins
- topoisomerase 2 then separates and relegates the interlinking strands