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)
1

What are the phases of the cell cycle? 

M -> G1 -> S -> G2

2

What happens in G1? 

Preparation for DNA replication

3

What happens in S phase?  

DNA replication

4

What happens in G2? 

Preparation for mitosis

 

 

5

Describe the chromosomes in each stage of the cell cycle

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

 

6

Describe the transitions between phases in the cell cycle? 

They occur in an orderly fashion 

7

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

Cyclin dependant kinases (CDKs)

8

What are CDKs? 

Seronine/theonine kinases

9

What do serine/theonine kinases do? 

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

10

What do the CDK substrates do? 

Promote cell cycle progression

11

When are CDKs active? 

When they are bound by their partners cyclins

12

How do CDK protein levels vary during the cell cycle? 

They are mainly stable 

13

What happens to cyclin levels during the cell cycle? 

They rise and fall 

14

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

Activation of CDK oscillates 

15

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

Cyclin, as its levels are rising and falling

16

What CDKs operate during G1? 

CDK4-6

17

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

Cyclin D1, D2, and D3

18

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

CDK2

19

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

Cyclin E1, E2

20

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

CDK2

21

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

Cyclin A1, A2

22

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

CDK1

23

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

Cyclin B1

24

What cyclins and CDKs are essential for entry into G1?

CyclinD/CDK4-6

25

What cyclins and CDKs regulate G1 to S progression? 

CyclinE/CDK2

26

What cyclins and CDKs are required during S and G2 phases

CyclinA/CDK2

27

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

Triggers DNA polymerase activity

28

What cyclins and CDKs promote entry into mitosis?

CyclinB/CDK1

 

 

29

What is RB? 

A tumour supressor gene

30

How does RB act as a tumour suppressor gene? 

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

31

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

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

 

32

What cyclin/CDK complex activates RB? 

Cyclin D and CDK4/6

33

How is Rb inactivated? 

Phosphorylation by cyclinE/CDK2

34

What regulates phosphorylation of Rb by cyclinE/CDK2? 

Cyclin E

35

What effect does the HPV virus have on Rb? 

It produces the E7 protein, which binds and inactivated Rb 

36

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

INK4 (INhibitor of Kinase 4)

 

37

What produces the INK4 complexes? 

  • p16 produces INK4a
  • p15 produces INK4b
  • p18 produces INK4c
  • p19 produces INK4d

 

38

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

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

39

What factors act as positive regulation CDK4? 

  • Growth factor
  • MAPK
  • Myc oncogene
  • PI3K/AKT

 

40

What acts as a negative regulator for cyclinE/CDK2? 

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

 

 

41

What produces the CIP and KIP proteins? 

  • p21 produces CIP1
  • p27 produces KIP1
  • p57 produces KIP2

 

42

What are the stages of mitosis? 

  1. Prophase
  2. Prometaphase
  3. Metaphase
  4. Anaphase
  5. Telophase

 

43

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

Prophase -> metaphase 

44

Why is it important to regulate prophase -> metaphase? 

Because there is no way back after metaphase

45

What promotes entry into M phase?

Cyclin A/CDK1 

46

What is essential for M phase progression into metaphase? 

CyclinB/CDK1

47

What does CDK1 do? 

Phosphorylates substrates involved in; 

  • Nuclear envelope breakdown
  • Chromosome condensation
  • Mitotic spindle assembly

 

48

What are cyclinA/B and CDK1 targets of? 

E2F

49