Week 4

Question 1

Which direction does the predominant helicase move in?

Answer 1

5’ to 3’ along lagging strand

Question 2

How do ssBPs do?

Answer 2

bind to ssDNA to prevent strands from H-bonding w/e/o

Question 3

What does primase make? What direction does it synthesize in?

Answer 3

makes RNA primers
5’ to 3’ along template strand (builds in 5’ to 3’)

Question 4

primosome

Answer 4

helicase + primase

Question 5

What reaction does DNAP catalyze? (2)

Answer 5

cuts off pyrophosphate and joins covalent linkage of nucleoside triphosphate into growing new strand

Question 6

What is the sliding clamp for?

Answer 6

holds DNAP on DNA

Question 7

How are RNA primers replaced?

Answer 7

nucleases remove primer and replaced with DNA by polymerase

Question 8

How does DNA ligase work? (2 steps)

Answer 8

1. ATP hydrolyzed
2. AMP released
   to form continuous DNA

Question 9

replisome

Answer 9

entire DNA replication machine

Question 10

Why does a loop form to bring DNAPs closer?

Answer 10

ALOSTERIC INTERACTION: binding to another polymerase functions more efficiently and work in same direction

Question 11

What 2 components make up an Okazaki fragment?

Answer 11

RNA primers + DNA

Question 12

What is topoisomerase and when is it most needed?

Answer 12

supercoiling in circular and large linear chromosomes
cuts DNA, allows it to spin, then reseals