DNA Replication

Question 1

enzyme that builds DNA

Answer 1

DNA polymerase

Question 2

What is the type of replication DNA undergoes?

Answer 2

Semi-conservative

Question 3

experiment that proved type of replication DNA undergoes

Answer 3

Meselson and Stahl
uses CsCl gradient
used heavy 15N nitrogen to grow bacteria. then placed in light 14N nitrogen and replication is done. strands became lighter leaving bands in centrifugation

Question 4

name of DNA strands during replication

Answer 4

leading strand and lagging strand

Question 5

fragments on lagging strand

Answer 5

Okazaki fragments

Question 6

DNA polymerase resembles a

Answer 6

right hand

Question 7

DNA polymerase alpha

Answer 7

eukaryotic DNA replication initiation

Question 8

DNA polymerase delta

Answer 8

eukaryotic DNA replication, lagging strand

Question 9

DNA polymerase epsilon

Answer 9

eukaryotic DNA replication, leading strand

Question 10

what is the fidelity of dNA replication?

Answer 10

1 mistake in 10^9 nucleotides

Question 11

extremely important for fidelity

Answer 11

proofreading

Question 12

Direction of proofreading?

Answer 12

goes in “opposite” direction. 3’-5’

Question 13

proofreading exonuclease has _____ active sites

Answer 13

2 active sites, P and E
polymerase catalytic site
exonuclease catalytic site

Question 14

fidelity of DNA polymerase

Answer 14

1 in 10^5

Question 15

fidelity of DNA proofreading

Answer 15

1 in 10^2

Question 16

fidelity of DNA strand-directed mismatch repair

Answer 16

1 in 10^2

Question 17

primase

Answer 17

creates 10 nucleotide primer
uses RNA
in eukaryotes, its par of DNA polymerase alpha complex

Question 18

lagging strand has primers every _____

Answer 18

100-200 nucleotides

Question 19

in eukaryotes the RNA primer is removed by

Answer 19

flap endonuclease

Question 20

closes gaps and nicks in DNA

Answer 20

DNA ligase I

Question 21

unwinds the DNA double helix

Answer 21

DNA helicase

named for the direction they move across the strand

Question 22

what is DNA helicase made of

Answer 22

MCM2-7 hexamer complex

Question 23

proteins that bind to single-stranded DNA

Answer 23

Eukaryotes- RPA (3 sub-units)

Question 24

sliding clamp name and function

Answer 24

DNA polymerase attaches to sliding clamp,

eukaryotes- homotrimer named PCNA

Question 25

alt name for sliding clamp

Answer 25

processivity factor

Question 26

sliding clamps bring

Answer 26

MANY different enzymes to the replication fork.

DNA ligase, flap endonuclease, repair systems, and chromatin assembly factors

Question 27

sliding clamps are loaded by

Answer 27

clamp loaders

eukaryotes, called RFC or replication factor-C

Question 28

clamp loaders require _______

Answer 28

ATP in order to load the sliding clamp

Question 29

enzymes that relieve super-twisting caused by unwinding and rewinding DNA

Answer 29

type I topoisomerase

Question 30

how does type I topoisomerase work

Answer 30

creates a nick in the DNA allowing it to rotate to relieve stress.
reaction is reversible

Question 31

can make double stranded breaks in DNA when DNA is tangled

Answer 31

Type II topoisomerase

Question 32

activities listed for DNA replication fork

Answer 32

1. Synthesis- sliding clamp and DNA polymerase
2. Unwinding- DNA helicase
3. Untwist DNA- topoisomerase
4. Priming- RNA primase, flap endonuclease to remove
5. Seal DNA- ligase to close nicks
6. Protection SSD- single-stranded binding proteins