Symes DNA Replication

Question 1

OriC

Answer 1

Replication initiation region in prokaryotes
- 3 AT-rich sequences
- 4 9bp sites (DNAa binding domain)

Question 2

DNAa

Answer 2

Initiatior proteins which binds causing the DNA to bend
- splits DNA apart
- binding mediated by positive histone-like proteins
- prokaryotic

Question 3

DnaB/C

Answer 3

Helicase which displaces DNAa
- prokaryotic

Question 4

SSBs

Answer 4

Stabilise ssDNA
- prokaryotic

Question 5

DnaG

Answer 5

Part of the primosome, makes primers
- prokaryotic

Question 6

Function of DNA Pol 1

Answer 6

Performs primer excision and DNA repair
- fills in gap left behind by primer
- prokaryotic

Question 7

What does the 3’ exonuclease of DNA Pol 1 do?

Answer 7

Proofreading, removes wrong base
- prokaryotic

Question 8

Function of 5’ exonuclease of DNA Pol 1

Answer 8

Removes primers (nick translation)
- prokaryotic

Question 9

Nick Translation

Answer 9

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

Question 10

DNA Pol III

Answer 10

Performs the bulk of replication in prokaryotes
- high processivity and high rate
- prokaryotic

Question 11

Subunits in core enzyme of DNA Pol III

Answer 11

Dimer of alpha, epsilon (3’ exo), theta
- prokaryotic

Question 12

beta sliding clamp

Answer 12

Part of DNA Pol III
- improves processivity
- negative amino acids on the interior
- prokaryotic

Question 13

Gamma complex

Answer 13

beta clamp loader
- chi subunit helps DNA Pol III transition form making RNA primer to making DNA

Question 14

Replisome

Answer 14

Creation of a loop at the replication fork so DNA Pol III can go in the same direction on both strands

Question 15

What perfroms proofreading in prokaryotes

Answer 15

Epsilon subunit of DNA Pol III removes the mismatched base with its 3’ to 5’ exonuclease

Question 16

How does termination in prokaryotes occur?

Answer 16

ter and TUS proteins
- topoisomerase 2 then separates and relegates the interlinking strands

Question 17

4 similarities between prokaryotic and eukaryotic replication

Answer 17

1) semi-conservative
2) Bi-directional
3) requires RNA primers
4) Leading strand and Okazaki fragments

Question 18

Prokaryotic initiation mechanism

Answer 18

Initiation begins at a single initiation site with additional rounds started before completion of the first round

Question 19

Prokaryotic Priming mechanism

Answer 19

Provides an unreacted 3’ OH to allow DNA Pol to bind
- RNA primer: 5-10 nts, made 5’ to 3’

Question 20

DNA Polymerase Gamma

Answer 20

Found in the mitochondria

Eukaryotic

Question 21

DNA Polymerase Beta

Answer 21

Responsible for DNA repair

Eukaryotic

Question 22

DNA Polymerase alpha

Answer 22

Contains the primase, makes RNA Primer
- no proofreading

Eukaryotic

Question 23

DNA Polymerase delta

What does it do?

Answer 23

Responsible for lagging strand replication
- combines with epsilon to fill in gap left behind by RNA primer

Eukaryotic

Question 24

DNA Polymerase Epsilon

Answer 24

Responsible for leading strand replication
- combines with delta to fill in gap left behind by RNA primer

Eukaryotic

Question 25

What happens to nucleosomes in eukaryotic replication?

Answer 25

Dissociate ahead of the fork, then resynthesize after it | Eukaryotic

Question 26

ORC

Answer 26

Binds next to AT-rich regions to bend DNA | Eukaryotic

Question 27

MCMs

Answer 27

Helicase - mini chromosome maintenance proteins | Eukaryotic

Question 28

RPA

Answer 28

SSBs - Replication Protein A | Eukaryotic

Question 29

PCNA

Answer 29

Beta-clamp | Eukaryotic

Question 30

RFC

Answer 30

Clamp loader - Replication Factor C | Eukaryotic

Question 31

RNase H/Fen1

Answer 31

Removal of RNA primers | Eukaryotic

Question 32

Licensing

Answer 32

Part of replication - assembly of pre-replication complex on ARS - pre-RC contains ORC, inactive MCMs, others | Eukaryotic

Question 33

ARS

Answer 33

Origin of replication | Eukaryotic

Question 34

Firing

Answer 34

Part of replication - Helicase is activated, activating the RC | Eukaryotic

Question 35

hTERT

Answer 35

Protein component of reverse transcriptase

Question 36

hTR

Answer 36

Template for hTERT - RNA component of reverse transcriptase

Question 37

t-loop

Answer 37

Leftover overhang which comes in and displaces dsDNA to make a D-loop-t-loop

Question 38

Dyskeratosis Congenita

Answer 38

Mutations in hTERT/hTR which cause premature mortality - example of anticipation

Question 39

Function of chi subunit of gamma subunit

Answer 39

Interacts with SSBs to transition DNA over to DNA Pol III for replication

Question 40

Which polymerase does PCNA increase the processivity of?

Answer 40

Delta