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HMS Oncology > Cell Division > Flashcards

Flashcards in Cell Division Deck (50):
1

Basic cell cycle outline

2

Graph of Cyclin Concentration Over Time

3

Cyclin-CDK / Cell Cycle Overlay

4

Cyclin / CDK model including Cyclin C-CDK3 and Cyclin H-CDK7

5

Role of Cyclin C-CDK3

Drives re-entry from G0

6

Role of Cyclin H-CDK7-MAT1

Enables Cyclin B-CDK1 activity

7

Role of Cyclin D-CDK4/6

Activated during G1 phase of the cell cycle. The level of cyclin D-CDK activity is important in helping the cell decide whether or not to divide. The higher the level of activity, the more likely it is to divide.

8

Role of Cyclin E-CDK2

9

Role of Cyclin A-CDK2

10

Role of Cyclin A-CDK1

11

Role of Cyclin B-CDK1

12

Regulation of Cyclin-CDKs

13

Three mechanisms of CDK regulation

1.  Synthesis and degradation (E3 ubiquitination) of cyclin and CDK subunits

2.  Regulation by other protein kinases and phosphatases

3.  Inhibitors of CDK activity (INKs)

14

Coordination of Growth and Cell Cycle Progression

15

Relevance of integrin signaling to cell division

16

Rb-E2F regulation

17

The INKs

18

Prokaryotic vs Eukaryotic DNA replication

19

Segregation of Origin Assembly and DNA Replication

20

Prereplication Complex Regulation

21

The prereplication complex is activated to begin transcription by. . .

E or A Cyclins and associated CDKs

22

Initiation of Replication

23

Rpa

Binds to ssDNA during replication to prevent it from reannealing.

24

Regulation of S phase replication

25

Pol δ

DNA Polymerase utilized in replication

26

PCNA

Keeps Pol δ attached to the DNA during replication

27

What keeps initiation factors from binding to the new strands of DNA that are being produced during replication?

Phosphorylation by high levels of Cyclin E/Cyclin A-CDK complexes

28

Sustained CDK activity during S phase and G2 is essential to . . .

1.  Promote completion of DNA replication

2.  Prevent re-initaition and re-replication of replicated DNA

29

Fundamental logic of the Cyclin-CDK solution to the problem of segregating replication and initiation

30

Mitosis imaged by fluorescence microscopy

31

Location of the G2-M Checkpoint

32

Wee1

Kinase which is activated by signaling from active DNA replication forks.  Phosphorylates Cyclin B-CDK1 complexes on two N-terminal residues (Thr14, Tyr 15) which inhibits Cyclin B-CDK1 activity. 

 

This prevents mitosis from starting until DNA replication is complete.

33

Cdc25

Phosphatase which is activated when replication forks disappear (replication is over)

 

Removes the inhibitory Thr14 and Tyr15 phosphate groups on Cyclin B-CDK1, which were placed by Wee1, and allows the cell to enter mitosis.

34

How Cyclin B-CDK1 breaks down the nuclear lamina

35

Condensation of DNA for mitosis

This condensation is mediated by Cyclin B-CDK1

36

Centromeres and Kinetochores

37

Cohesin

38

Cohesins are cut as part of the _____ to _____ transition.

Cohesins are cut as part of the metaphase to anaphase transition.

39

During mitosis, the Golgi and ER. . .

. . .become fragmented into vesicles and are passively distributed to the two daughter cells.

40

Bipolar attachment

Each sister chromatid in a single chromosome is attached to microtubules coming from one end of the mitotic spindle

41

Metaphase-Anaphase Checkpoint Location

42

Sequences Required for Cyclin B degradation

43

Degron

Sequence that targets the protein for regulated degradation (not necessarily constitutive)

44

The E3 for Cyclin B is. . .

APC/C

aka

Anaphase promoting complex / cyclosome

 

(Not to be confused with adenomatous polyposis coli, the tumor suppressor gene product, or antigen presenting cell)

45

Role of Cdc20 in Cyclin B regulation

Cdc20 is the receptor which associates with the APC/C complex in order to target Cyclin B for degradation.

 

Cdc20 recognizes only phosphorylated Cyclin B, and so it will not degrade Cyclin B prior to the metaphase-anaphase transition.

46

Securin

Inhibits separase until APC/C is activated.  It senses APC/C activation because. . . it is an APC/C target! 

This is how Cyclin B-CDK1 destruction is tied to the beginning of anaphase:    Once APC/C is active, all of the sudden Cyclin B-CDK1 and securin are both gone.

47

The Separase-Securin System

48

_____ is what is sensed by the spindle checkpoint

Tension is what is sensed by the spindle checkpoint

 

If a chromosome is not under tension, it means is must not be attached properly, and thus the spindle checkpoint is activated.

49

Drop in CDK activity at the end of mitosis and cytokinesis leads to. . .

. . . inactivating dephosphorylation of the proteins that form pre-replication complexes.

 

These will be reactivated after the G1/S transition.

50

We can boil down the logic of the cell cycle to an oscillation between. . .

We can boil down the logic of the cell cycle to an oscillation between CDK activity and APC/C activity