dna Rep Bac Flashcards
DNA replication terminates at what degree from origin.
180
Replication bubble forms having what on each end
Replication fork
DNA Polymerase requires what 4 things
1) Primer DNA with free 3’ OH
2) Template DNA to specify the sequence of the new strand
3) Substrates - dNTPs
4) Mg2+
DNA replication is what
Bi directional
DNA polymerase 1 does what
Clean up - nicks
5’ to 3’ exonuclease
Abundant, not ideal for replication
Low processivity
DNA pol 3 is for what
Replication
DNA pol 2/4/5 is for
Repair
All DNA polymerase have what
Exonuclease in 3’ to 5’ direction
What is the klenow fragment
Large protein fragment
Retains 5’ to 3’ polymerase activity
Retains 3’ to 5’ polymerase activity
Loses 5’ to 3’ exonuclease activity
When is the klenow fragment produced
When DNA pol 1 undergoes protease treatment
Why does the klenow fragment retain polymerase activity
For removal of primer nucleotides and proofreading
A nick is what
A broken phosphodiester bond leaving 3’hydroxyl and free 5’ phosphate
Where is the nick usually found
At the beginning of DNA synthesis
What DNA polymerase repairs the nick but also does what
Pol 1 repairs the nick but leaves a nick when it dissociates off
What are the two core domains in Pol3 composed of
Alpha, epsilon and a theta
The two core domains in DNA pol 3 is linked by what complex
Clamp loading 5 subunit y complex
The clamp loading 5 subunit y complex is made of what subunits
2 τ units (dnaX)
1 γ unit (also dnaX)
1 δ subunit (holA), and 1 δ’ subunit (holB)
Hugh
The core domains each interact with what
A dimer of β units (dnaN)
2 β units (dnaN) act as what in DNA pol 3
Act as sliding DNA clamps
They keep the polymerase bound to the DNA - increase processivity
the α subunit is encoded by what gene and does what
encoded by the dnaE gene) has the polymerase activity
the ε subunit is encoded by what gene and does what
(dnaQ) has 3’→5’ exonuclease activity
the θ subunit is encoded by what gene and does what
holE and stimulates the ε subunit’s proofreading
2 τ units is encoded by what gene and does what
(dnaX) which acts to dimerize two of the core enzymes (α, ε, and θ subunits).
1 γ unit is encoded by what gene and does what
dnaX
Acts as a clamp loader for the lagging strand Okazaki fragments, helping the two β subunits to form a unit and bind to DNA.
δ does what in pol 3
The δ is involved in copying of the lagging strand.
How does the pol3 complex Interact with the DNAB helicase
Through the t subunit
DNA replication in ecoli requires
Replisome
Replisome is made of what 5 things
Helicase (uses atp) Topoisomerases (DNA gyrase, supercoiling) DNA single strand binding Primase - for RNA Primer DNA Ligase - seals nicks
