Replication Flashcards
A segment of nucleic acid (RNA or DNA) base paired to the template and with a free 3’-OH is called a
Primer
DNA polymerase and all synthesizing enzymes require a
Primer
Which end do DNA polymerases add bases to?
3’ end
Which direction is DNA synthesized?
5’ to 3’ direction
Which DNA polymerase has the following characteristics? structural gene= polA role= repair, primer, removal subunits= 1 Mr= 103,000 3'-->5' exonuclease= yes 5'-->3' exonuclease= yes polymerization rate= 16-20. processivity= 3-200.
DNA polymerase I of E. Coli
Which DNA polymerase has the following characteristics? structural gene= pol B role= specialized repair subunits= 7 Mr= 88,000 3'-->5' exonuclease= yes 5-->3' exonuclease= no polymerization rate= 40 processivity= 1500
DNA polymerase II of E. Coli
Which DNA polymerase has the following characteristics? structural gene= polC subunits= more than 10 Mr= 791,500 3'-->5' exonuclease= yes 5'-->3' exonuclease= no polymeraization rate= 25-1000 processivity= more than 500,000
DNA polymerase III of E. Coli
What does dnaA do in the initiation of replication?
Binds to oriC and forms intial complex
What does local denaturation do in the initiation of replication?
Opens complex
What do dnaB/dnaC do in the initiation of replication and what does this process create?
DnaB (a helicase) and dnaC dimers bind to open complex and unwind origin DNA to expose single strand template.
This process creates the prepriming complex.
What does SSB do in the initiation of replication?
SSB binds to single stranded DNA and stablizes it.
What is required in all steps that initiate replication?
ATP
What binds to dnaB/dnaC on DNA templates?
Primase
What is required to make a primosome and what does this create?
Primase and other proteins.
This creates a primer for DNA polymerase.
A DNA polymerase III dimer binds to primosome to form what?
A replisome.
What kind of synthesis begins at each fork using one DNA polymerase III molecule, the RNA primer, and the leading strand template?
Leading strand synthesis.
What is initiated by forming a loop of the lagging strand template on the replisome?
Elongation
What locally reverses the orientation of the lagging strand template with respect to the direction of movement of the replisome?
Elongation
What in the primosome synthesizes RNA primer?
Primase
What molecule binds primer and begins synthesis of the lagging strand?
DNA polymerase III
What synthesizes genes in eukaryotes?
DNA polymerase alpha (not separate primase enzyme as in prokaryotes).
What removes genes in eukaryotes?
RNAse H (not component of DNA polymerase I as in prokaryotes).
What limits the size of Okazaki fragments?
nucleosomes
What kind of proteins are synthesized during S phase and complex with newly synthesized DNA?
Histone proteins.
