Cell Cycle Control and Cancer Flashcards Preview

SSC- Biology of Cancer > Cell Cycle Control and Cancer > Flashcards

Flashcards in Cell Cycle Control and Cancer Deck (49)
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1
Q

What are the phases of the cell cycle?

A

M -> G1 -> S -> G2

2
Q

What happens in G1?

A

Preparation for DNA replication

3
Q

What happens in S phase?

A

DNA replication

4
Q

What happens in G2?

A

Preparation for mitosis

5
Q

Describe the chromosomes in each stage of the cell cycle

A
  • In G1, 2N (diploid)
  • In S, replication, so 2N -> 4N
  • In G2, 4N (tetraploid)
  • In mitosis, 4N -> 2N
6
Q

Describe the transitions between phases in the cell cycle?

A

They occur in an orderly fashion

7
Q

What are the key regulators of the transitions between different stages in the cell cycle?

A

Cyclin dependant kinases (CDKs)

8
Q

What are CDKs?

A

Seronine/theonine kinases

9
Q

What do serine/theonine kinases do?

A

Phosphorylate substrates at SER/THR-PRO-X-LYS/ARG motifs

10
Q

What do the CDK substrates do?

A

Promote cell cycle progression

11
Q

When are CDKs active?

A

When they are bound by their partners cyclins

12
Q

How do CDK protein levels vary during the cell cycle?

A

They are mainly stable

13
Q

What happens to cyclin levels during the cell cycle?

A

They rise and fall

14
Q

What is the result of the rising and falling of cyclin levels during the progression of the cell cycle?

A

Activation of CDK oscillates

15
Q

Does CDK or cyclin dictate the progression of the cell cycle?

A

Cyclin, as its levels are rising and falling

16
Q

What CDKs operate during G1?

A

CDK4-6

17
Q

What cyclins are involved in the G1 phase of the cell cycle?

A

Cyclin D1, D2, and D3

18
Q

What CDKs are involved in the G1/S phase of the cell cycle?

A

CDK2

19
Q

What cyclins are involved in the G1/S phases of the cell cycle?

A

Cyclin E1, E2

20
Q

What CDKs are involved in the S phase of the cell cycle?

A

CDK2

21
Q

What cyclins are involved in the S phase of the cell cycle?

A

Cyclin A1, A2

22
Q

What CDKs are involved in the M phase of the cell cycle?

A

CDK1

23
Q

What cyclins are involved in the M phase of the cell cycle?

A

Cyclin B1

24
Q

What cyclins and CDKs are essential for entry into G1?

A

CyclinD/CDK4-6

25
Q

What cyclins and CDKs regulate G1 to S progression?

A

CyclinE/CDK2

26
Q

What cyclins and CDKs are required during S and G2 phases

A

CyclinA/CDK2

27
Q

What do cyclinA/CDK2 do during S and G2 phases?

A

Triggers DNA polymerase activity

28
Q

What cyclins and CDKs promote entry into mitosis?

A

CyclinB/CDK1

29
Q

What is RB?

A

A tumour supressor gene

30
Q

How does RB act as a tumour suppressor gene?

A

Rb binds to E2F, which inhibits it from transcribing its S-phase genes

31
Q

What are the S phase genes produced by E2F responsible for?

A
  • DNA synthesis
  • DNA replication
  • DNA repair
  • Regulation (via Cyclin E and Cyclin A)
32
Q

What cyclin/CDK complex activates RB?

A

Cyclin D and CDK4/6

33
Q

How is Rb inactivated?

A

Phosphorylation by cyclinE/CDK2

34
Q

What regulates phosphorylation of Rb by cyclinE/CDK2?

A

Cyclin E

35
Q

What effect does the HPV virus have on Rb?

A

It produces the E7 protein, which binds and inactivated Rb

36
Q

What acts as negative regulation of the cyclinD and CDK4/6 complex?

A

INK4 (INhibitor of Kinase 4)

37
Q

What produces the INK4 complexes?

A
  • p16 produces INK4a
  • p15 produces INK4b
  • p18 produces INK4c
  • p19 produces INK4d
38
Q

How do the INK complexes act as negative regulators of CDK4?

A

They bind CDK, and block interaction with cyclin so the complex cannot form and therefore it cannot be activated

39
Q

What factors act as positive regulation CDK4?

A
  • Growth factor
  • MAPK
  • Myc oncogene
  • PI3K/AKT
40
Q

What acts as a negative regulator for cyclinE/CDK2?

A

CDK-interacting protein (CIP) or kinase inhibitor protein (KIP)

41
Q

What produces the CIP and KIP proteins?

A
  • p21 produces CIP1
  • p27 produces KIP1
  • p57 produces KIP2
42
Q

What are the stages of mitosis?

A
  1. Prophase
  2. Prometaphase
  3. Metaphase
  4. Anaphase
  5. Telophase
43
Q

What is the most important phase of mitosis to be regulated?

A

Prophase -> metaphase

44
Q

Why is it important to regulate prophase -> metaphase?

A

Because there is no way back after metaphase

45
Q

What promotes entry into M phase?

A

Cyclin A/CDK1

46
Q

What is essential for M phase progression into metaphase?

A

CyclinB/CDK1

47
Q

What does CDK1 do?

A

Phosphorylates substrates involved in;

  • Nuclear envelope breakdown
  • Chromosome condensation
  • Mitotic spindle assembly
48
Q

What are cyclinA/B and CDK1 targets of?

A

E2F

49
Q
A