2.1.6a&b The Cell Cycle and Cell Cycle Regulation

Question 1

What are the stages within interphase?

Answer 1

G1, S, G2

Question 2

What happens during interphase of the cell cycle?

Answer 2

The cell grows and copies its DNA, all in preparation of mitosis

Question 3

What happens during the G1 phase of the cell cycle?

Answer 3

• Cell grows bigger
• Cell replicates organelles
• High amount of protein synthesis takes place
• Overall, the cell is preparing to replicate DNA

Question 4

What happens during the S phase of the cell cycle?

Answer 4

• All genetic information in the cell is copied via DNA replication
• Sister chromatids are formed as a result of this
• Centrosomes duplicate to help separate DNA during mitosis

Question 5

What happens during the G2 phase of the cell cycle?

Answer 5

• Cell grows more
• Organises cell components for division
• Energy stores and nutrients increased

Question 6

What happens during the G0 phase of the cell cycle?

Answer 6

• The cell is neither dividing nor preparing to divide
• This could be a result of failing at the checkpoints or lacking the nutrients to continue with the cell cycle

Question 7

What are the 3 checkpoints involved in the cell cycle?

Answer 7

G1 checkpoint, G2 checkpoint, spindle checkpoint

Question 8

Where in the cell cycle does the G1 checkpoint occur?

Answer 8

At the end of G1 phase, just before S phase

Question 9

What does the G1 checkpoint check?

Answer 9

• Cell size
• Nutrients
• Growth factors
• DNA damage

Question 10

What happens if a cell does not meet the G1 checkpoint requirements?

Answer 10

the cell will go into G0 phase

Question 11

Where in the cell cycle does the G2 checkpoint occur?

Answer 11

at the end of G2 phase, before mitosis

Question 12

What does the G2 checkpoint check?

Answer 12

• Cell size
• DNA replication completeness from S phase
• DNA damage

Question 13

What happens if a cell does not meet the G2 checkpoint requirements?

Answer 13

• The cell will pause the cell cycle to carry out repairs
• DNA Repairable damage: cell cycle is halted so that DNA can finish replicating or to repair damaged DNA
• DNA irreparable damage: cell undergoes apoptosis

Question 14

Where in the cell cycle does the spindle checkpoint occur?

Answer 14

mitosis; between metaphase and anaphase

Question 15

What does the spindle checkpoint check?

Answer 15

if all sister chromatids are correctly attached to the spindle fibres

Question 16

Why is the spindle checkpoint important?

Answer 16

The cell cycle will not continue untill all chromosomes are firmly attached to at least 2 spindle fibres of opposing poles of the cell. The separation of sister chromatids in anaphase is irreversible so it is important to get this right

Question 17

How is the spindle checkpoint checked?

Answer 17

by looking for straggler chromosomes which are in the wrong place

Question 18

how are ‘straggler’ chromosomes corrected when detected by the spindle checkpoint?

Answer 18

mitosis will be paused to allow spindle fibres to capture the stray chromosomes