DNA Replication, The Cell Cycle and Mitosis

Question 1

What does DNA polymerase require?

Answer 1

template strand, oligonucleotide primer, supply of dNTPs

Question 2

Define replication fork

Answer 2

sites of DNA synthesis

Question 3

Define leading strand

Answer 3

strand that is continuously synthesised in 5’ to 3’ direction

Question 4

Define lagging strand

Answer 4

synthesised in short fragments called okazaki fragments in 5’ to 3’ direction

Question 5

Function of DNA primase

Answer 5

synthesises short RNA fragment

Question 6

What does each okazaki fragment require?

Answer 6

individual primer

Question 7

Function of ribonuclease

Answer 7

remove RNA primer using 5’ to 3’ exonuclease activity

Question 8

Function of repair DNA polymerase

Answer 8

replaces RNA primer with DNA

Question 9

What enzyme joins 2 okazaki fragments?

Answer 9

DNA ligase

Question 10

Why is there a proof reading mechanism?

Answer 10

ensures no mistakes, errors can’t be repaired, checks base pairing before next nucleotide added

Question 11

Summarise bacteria DNA replication

Answer 11

replication starts at origin, 2 replication forks in opposite directions, meet on other side

Question 12

Name the phases of the cell cycle in order

Answer 12

M, G1, S, G2, G0,

Question 13

Describe M phase

Answer 13

mitosis/cell division

Question 14

Describe G1 phase

Answer 14

gap phase, prior to DNA synthesis, 10 hours

Question 15

Describe S phase

Answer 15

DNA synthesis, replication, 9 hours

Question 16

Describe G2 phase

Answer 16

gap phase, 4 hours

Question 17

Describe G0 phase

Answer 17

cells stop dividing

Question 18

Name the 2 divisions of the cell cycle

Answer 18

interphase and mitosis