EXAM 3

Question 1

Enzyme that opens double stranded DNA for replication

Answer 1

HELICASE (DNA replication)

Question 2

Enzyme that removes supercoils during replication

Answer 2

DNA GYRASE, or TOPOISOMERASE II in humans.

Question 3

Protein that prevents single strands of DNA from reannealing during replication

Answer 3

SSB, or Single Stranded Binding protein.

Question 4

Enzyme that synthesizes new DNA strand from templates during replication

Answer 4

DNA POLYMERASE III

Question 5

3 things needed for DNA replication to begin?

Answer 5

1. A template to copy
2. an RNA primer to add nucleotides at 3’ end
3. a free 3’ end

Question 6

Enzyme that synthesizes RNA primers

Answer 6

PRIMASE

Question 7

Enzyme that binds together Okazaki fragments

Answer 7

LIGASE

Question 8

Enzyme that removes RNA primers and replaces them with DNA

Answer 8

DNA POLYMERASE I

Question 9

Enzyme that cleaves one nucleotide at a time

Answer 9

EXONUCLEASE

Question 10

3 things that damage DNA

Answer 10

UV light
Radiation
Free radicals

Question 11

Enzyme that discovers defects and can excise a base

Answer 11

GLYCOSYLASE

Question 12

BASE EXCISION REPAIR

Answer 12

mismatched base pairs which can cause mutations are discovered by GLYCOSYLASE, which removes the base. DNA polymerase I fills in gap, Ligase seals the strand.

Question 13

NUCLEOTIDE EXCISION REPAIR

Answer 13

Two T’s bond together on the same strand. Exonuclease cuts the strand, 12 nucleotides removed. DNA pol I fills in the gaps, ligase seals the strand.

Question 14

MISMATCH REPAIR

Answer 14

Mismatched base pairs. New strand is cut and mismatch removed. DNA pol I fills in gaps, ligase seals the strand.