2. DNA replication

Question 1

DNA polymerase substrate requirements

Answer 1

• template
• primer
• free OH group at the 3’ end

Question 2

helicase

Answer 2

a processive enzyme that must be loaded onto DNA. unzips DNA at replication forks

Question 3

topoisomerase

Answer 3

removes supercoils so DNA remains negatively supercoiled

Question 4

single strand binding proteins

Answer 4

protect ssDNA

Question 5

sliding clamp and clamp loader

Answer 5

helps polymerase stay on DNA lol

Question 6

DNAprimase

Answer 6

synthesises and adds RNA primers

Question 7

replisome

Answer 7

polymerases +accessory enzymes

Question 8

prokaryotic polymerases

Answer 8

Pol III - DNA replication
Pol I & II - DNA repair

Question 9

OriC

Answer 9

defined point for DNA synthesis initiation in prokaryotes

Question 10

ter site

Answer 10

prokaryotic one-way valves where replication forks can enter but not leave

Question 11

yeast initiation sites

Answer 11

autonomously replicating sequences

Question 12

higher eukaryotic initiation sites

Answer 12

ORC at multiple undefined sites

Question 13

eukaryotic polymerases

Answer 13

> 13
used in DNA replication
- alpha: synthesis of RNA-DNA primers, start of okazaki fragments
- delta: lagging strand pol
- epsilon: leading strand pol

Question 14

RNAse H1

Answer 14

eukaryotic- removed RNA primers

Question 15

FEN 1

Answer 15

eukaryotic- removes pol alpha DNA

Question 16

telomerase maintenance negatives

Answer 16

if cells don’t die as they get older they buildup mutations, which can cause health issues

Question 17

possible DNA replication disorders

Answer 17

• cancer
• microcephaly (replication during neurogenesis
• primordial dwarfism (orc1 variant -> fewer replication origins -> less cells)

Question 18

DNA Pol fidelity

Answer 18

• mistakes ~1 per 100,000
• error correction: exonuclease
• retained mistakes ~ 1 per 10,000,000,000