IASM 30: Cell Division and Cell Cycle

Question 1

There are 4 phases in the cell cycle. Name them in order

Answer 1

G1
S
G2
M

Question 2

What will happen in the following stages?
G1 (No need)
S
G2 
M

Answer 2

G1
S: DNA Replication
G2: Growth of organelles
M: Division

Question 3

When is G1 Checkpoint

Answer 3

Right before entering S Phase

Question 4

When is G2 Checkpoint

Answer 4

Right before entering M Phase

Question 5

When is the mitotic checkpoint

Answer 5

Right before chromosomes pulling apart in anaphase

Question 6

How to pass G2 Checkpoint

Answer 6

When it is confirmed that all DNAs are replicated

Question 7

How to pass mitotic checkpoint

Answer 7

All chromosomes are attached properly to the mitotic spindle

Question 8

Explain, in terms of biochemical molecules, how does G1 Phase proceed to S Phase

1. _______________ phosphorylate ________
2. Release ____________
3. Trigger _____________, enter S phase
4. Further phosphorylate _______ (positive feedback)

Answer 8

1. Cyclin D Cdk 4/6 phosphorylate RB
2. Release Rb-bound E2F
3. Trigger Cyclin E, enter S phase
4. Further phosphorylate RB (positive feedback)

(D => RB => E2F => E)
Involves Cyclin D and Cyclin E

Question 9

Explain, in terms of biochemical molecules, what happens during the M phase

• __________ causes breakdown of _______________
• Inactive ________ to Active ___________
• By turning inactive __________________ to active ________________

Answer 9

• Cyclin B Cdk causes breakdown of nuclear envelope
• Inactive M Cdk to Active M Cdk
• By turning inactive Cdc25 phosphatase to active Cdc25 phosphatase

(B => M => Cdc25)
Involves Cyclin B and M

Question 10

P53 and P21 are…

Answer 10

Universal inhibitors of the cell cycle

Question 11

How does cell cycle terminate with reference to the biochemical molecules

\_\_\_\_ is activated
\_\_\_\_\_ bind to \_\_\_\_\_\_\_
Formation of \_\_\_\_\_\_\_\_\_ by \_\_\_\_\_\_\_\_\_\_\_
Formation of \_\_\_\_\_\_\_\_\_ by \_\_\_\_\_\_\_\_\_\_
\_\_\_\_\_\_\_\_ complexes with \_\_\_\_\_\_\_\_\_\_\_\_ to stop the cell cycle

Answer 11

p53 is activated
p53 bind to p21
Formation of p21 mRNA by transcription
Formation of p21 protein by translation
p21 complexes with Cyclin-Cdk complex to stop the cell cycle