DNA replication proteins

Question 1

DNA polymerases

Answer 1

Add nucleotides to a strand growing 5’ to 3’, copying a DNA template 3’ to 5’

Question 2

Primase

Answer 2

Synthesizes RNA primers

Question 3

Helicase

Answer 3

Separates parental DNA strands, i.e., unwind the double helix

Question 4

Single-stranded binding proteins

Answer 4

Prevent single strands of DNA from re-associating

Question 5

Topoisomerases

Answer 5

Relieve torsional strain on parental duplex caused by unwinding

Question 6

Enzymes that remove primers

Answer 6

RNase H hydrolyzes RNA of DNA-RNA hybrids
Flap endonuclease 1 (FEN1) recognizes “flap” (unannealed portion of RNA) near 5’-end of primer and cleaves downstream in DNA region of primer; the flap is created by polymerase delta displacing the primer as the Okazaki fragment is synthesized

Question 7

DNA ligase

Answer 7

Joins, by forming a phosphodiester bond, two adjacent DNA strands that are bound to the same template

Question 8

PCNA

Answer 8

Enhances processivity of the DNA polymerases; binds to many proteins present at the replication fork

Question 9

DNA Pol α

Answer 9

Replication (in a complex with primase and aids in starting the primer)
DNA repair
No exonuclease activity

Question 10

DNA Pol β

Answer 10

DNA repair exclusively

No exonuclease activity

Question 11

DNA Pol γ

Answer 11

DNA replication in mitochondria

3’ to 5’ exonuclease activity

Question 12

DNA Pol δ

Answer 12

Replication (processive DNA synthesis on lagging strand)
DNA repair
3’ to 5’ exonuclease activity

Question 13

DNA Pol ε

Answer 13

Replication (processive DNA synthesis on leading strand)
DNA repair
3’ to 5’ exonuclease activity

Question 14

DNA Pol κ, η, ξ, ι

Answer 14

DNA repair (bypass polymerase)
No exonuclease activity