DNA Replication-Lecture 8/17/21

Question 1

ORC

Answer 1

Origin recognition complex- recognizes origin in eukaryotic DNA, not like prokaryotic DNA

Question 2

MCM complex

Answer 2

Helicase complex that uses energy from ATP to unwind DNA

Question 3

Human SSB (RPA)

Answer 3

single strand binding protein, binds to single stranded DNA to prevent re-annealing

Question 4

Topoisomerase I

Answer 4

Changes the topology of the DNA to make it accessible

Question 5

Pol a-primase

Answer 5

Initiates DNA synthesis, makes RNA and DNA primers

Question 6

Pol delta

Answer 6

Required for lagging strand synthesis (PCNA dependent)

Question 7

Pol epsilon

Answer 7

Required for leading strand synthesis (PCNA dependent)

Question 8

Chain elongation

Answer 8

Nucleophilic attack of 3’ hydroxyl group on the alpha-phosphate

Question 9

Polymerase switch

Answer 9

From pol alpha-> pol delta or epsilon, mediated by PCNA

Question 10

PCNA

Answer 10

Acts as a clamp around DNA to keep polymerase on

Question 11

Okazaki fragments

Answer 11

Fragments of synthesized DNA on the lagging strand

Question 12

Exonuclease activity

Answer 12

3’->5’ , excises and replaces misplaced base pairs

Question 13

DNA ligase

Answer 13

Fuses fragments together

Question 14

DNA polymerase gamma

Answer 14

mitochondrial DNA replicatiom

Question 15

DNA polymerase beta

Answer 15

Repair DNA synthesis

Question 16

Cell cycle

Answer 16

G1->S->G2->M->

Question 17

p53

Answer 17

Tumor suppressor, Major checkpoint between G1 and S that prevents the cell from replicating damaged DNA, mutated or missing in 50% of cancers

Question 18

Li-Fraumeni syndrome

Answer 18

Born with defective P53

Question 19

Mismatch repair

Answer 19

Repairs incorrectly matched DNA pairs, recognizes which is “correct” old DNA by looking for methyl group and resynthesizing

Question 20

Uracil-DNA glycosidase

Answer 20

Exices uracil and replaces with C