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Flashcards in cell cycle control Deck (52):
1

What doe half the cell cycle constitute?

S phase

2

How long is M phase?

a short time

3

What is M phase responsible for?

Nuclear division
Cytoplasmic division

4

What happens in the S phase?

synthesis of DNA

5

What takes place in mitosis?

M-phase cytokinesis
cytokinesis

6

What are the phases of mitosis?

Prophase
prometaphase
metaphase
anaphase
telophase
cytokinesis

7

What is the state of the chromosomes in interphase?

the are unwinded and they can hardly be seen

8

What happens in interphase right before Mphase begins?

chromosomes start to condense

9

When does the nuclear envelope breaks up?

prometaphase

10

When does the chromosomes associate their kinetichores with mitotic spindles?

prometaphase

11

what happens in metaphase?

chromosomes line up at the equator

12

what happens in anaphase?

sister chromatids are pulled apart to opposite ends

13

What is the metaphase to anaphase transition?

the glue that holds the sister chromatids together disintegrates

14

What happens in telophase?

contractile ring of actin and myosin forms
nuclear membrane starts to reform

15

What happens in cytokinesis?

Cytoplasm is split into two

16

What phase is cell growth and accumulation of cell mass?

G1
G2

17

What are the four sequential phases?

G1
S
G2
M

18

What is the G0 phase?

Resting phase
if conditions are not right for dividing cells stay in this phase. can extend for an indefinite period

19

Why are yeast the model system to study the cell cycle?

Rapid reproduction
Genome size 1% of humans
amendable to genetic manipulations
can proliferate in the haploid state

20

What did mutations of the yeast genome allow for the discovery of?

Cell division cycle genes (Cdc genes)

21

How are Cdc mutants cell cycle studied?

They were arrested at different points in the cell cycle

22

How are Cdc mutants arrested?

There are temperature sensitive mutants established.
They can grow at permissive temps then change the temp and the cell will stop at that point in the cell cycle

23

What cells can you use to analyze the cell cycle and why?

Xenopus eggs
100000 times more cytoplasm than humans/easy ti inject test substance in large xenopus eggs

24

When does rapid cell division occurs in Xenopus eggs?

early in embryogensis without growth signals and control mechanisms of other complex cell cycles

25

How can you look at the cell cycle progression?

under the microscope (mitosis, cytojinesis)
DNA binding stains or specific antibodies(reveal condensation state)

26

What is a sphase identifier?

incorporation of BrdU

27

How can you measure DNA content?

DNA binding dyes and flow cytometry

28

What are the major regulatory transition points?

Start or restriction point
G2/M checkpoint
Metaphase - to anaphase

29

What else is flow cytometry known as?

Fluorescence activating cell sorting (FACS)

30

When is the start checkpoint?

at the end of G1 right before S phase

31

What is the cell checking for at the the start checkpoint?

is the environment correct to proceed int o S phase
it is a restriction point. once past this point cannot turn around

32

When is the G2/M phase checkpoint?

end of G2 before Mphase

33

What is the cell checking for at the G2/M phase check point?

is all DNA replicated
is environment favorable

34

What is the cell checking for at the Metaphase to anaphase transition?

are all the chromosomes attached to the spindle

35

If all the chromosomes are attached to the spindle what does it trigger?

trigger anaphase to and proceed to cytokinesis

36

What are the regulators of of the cell cycle?

Cyclin dependent kinases (Cdks)
they are activated by cyclin binding

37

What protein regulate Cdks?

Cyclins

38

What are the different cyclins?

G1/S
S cyclins
M cyclins
G1 cyclins

39

When are G1/S cyclins active?

late G1

40

When S cyclins actives?

start point until mitosis

41

When are M cyclins active?

at G2/M phase

42

When are G1 cyclins active?

G1 through start point

43

What protein is active at the anaphase to metaphase transition point?

anaphase promoting complex/cyclosome (APC/C)

44

What are APC/C involved in?

degradation of M cyclins

45

How are Cdks activated?

1) cyclin binding (exposes active site)
2)Cdk activating kinase (phosphorylates Cdks)

46

How are Cdks inactivated?

1) Wee1 kinase (adds two inhibitory phosphates)

47

What removes the Wee1 inhibitory phosphate?

Cdc25 phosphotase

48

What are CKIs?

Cdk inhibitory protein
p27 is one type
p21 is one type

49

When is the Cdk inactive?

no cyclin bound
active site blocked

50

when is the Cdk partly activated?

When the cyclin binds and the active site block forms a t loop

51

When is Cdk fully activated?

phosphorylation of the binding site by Cdk activating protein

52

How does p27 Cki bind to an active kinase?

it binds to both the Cdk and cyclin it changes the conformation of the binding site to inactive form

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