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lecture 21 Flashcards

1
Q

when do we see declines in cyclin

A

once the transition is triggered, we see a decline

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2
Q

what cyclins directly induce replication of DNA

A

S cyclins

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3
Q

what complex signals destruction of the M cyclin half way through mitosis

A

anaphase-promoting complex

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4
Q

what is the MAP complex

A

M cyclin-Cdk complex (maturation promoting factor)

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5
Q

what is the Cdk and the cyclin involved in MAP

A

Cdk 1
Cyclin B

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6
Q

where is MAP located

A

G2 checkpoint

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7
Q

what does MAP do

A

it phosphorylates targets to trigger mitotic changes (ex. to break down membranes)

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8
Q

where does cyclin bind Cdk

A

at its flexible T loop - away from active site opening to partially activate

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9
Q

what does full activation of Cdk require

A

phosphorylation of threonine residue near Cdk active site

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10
Q

what phosphorylates threonine on Cdk to make it fully active

A

Cdk-activating kinase

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11
Q

whats the primary determinant of Cdk activity

A

the rise and fall of cyclin levels

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12
Q

what does phosphorylation by protein kinase Wee1 to do to Cdk

A

inhibits activity

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13
Q

what does dephospho rylation by phosphatase Cdc25 do to Cdk

A

increases activity

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14
Q

where is phosphorylation/dephosphorylation important in control of Cdk

A

beginning of mitosis (S phase)

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15
Q

what inhibits Cdk in G1 regarding budding yeast

A

Sic1 inhibits Cdk in G1

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16
Q

what inhibits cyclin A-Cdk2 complex in humans in the S phase

A

P27

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17
Q

what is regulated proteolysis

A

breaking down of Cdk

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18
Q

what happens to cyclins at the end of each phase of the cell cycle

A

proteolysis

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19
Q

what complex is found at the M checkpoint

A

anaphase promoting complex

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20
Q

what is the anaphase promoting complex

A

contains ubiquitin ligases that tag and target S and M cyclins to trigger the transition from metaphase to anaphase

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21
Q

at what stage do the chromosomal microtubules attach to kinetochores

A

prometaphase

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22
Q

when does cytokinesis start

A

anaphase

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23
Q

what is division of the cell called

A

cytokinesis

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24
Q

what separates the cell in animal cells

A

cleavage furrow

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25
what separates the cell in plant cells
a cell plate
26
when does chromosome compaction/condensation occur
early prophase
27
what protein is responsible for compaction of chromosomes in prophase
Condensin
28
is condensin energy dependent
yes
29
does condensin help form the chromosome X shape
yes
30
what is cohesion
it holds sister chromatids together through G2 and mitosis
31
what do both cohesion and condensin contain
SMC proteins (structural maintenance of chromosome)
32
whats the structure of SMCs
they fold back on themselves and form an anti parallel coiled coil
33
what protein is responsible for looping chromosomes in prophase
condensin
34
whats the structure of a centormere
constricted region of mitotic chromosome with highly repeated DNA sequences
35
whats a kinetochore
protein complex that assembles on centromere
36
what attaches chromosome to spindle microtubules
kinetochore
37
what are the two regions of a kinetochore
inner and outer
38
what creates the 2 poles on either side of the cell
centrosome
39
whats the principle microtubule organizing centre in animal cells
centrosome
40
when do centrosomes separate
at the beginning of mitosis
41
what is an aster
array of microtubules round centrosomes
42
what is the separation of asters triggered by
the enzyme separase
43
what inactivates stabilizing proteins in prophase
MAPs
44
how is the nuclear membrane disrupted mechanically
cytoplasmic dynein molecules tear holes in the nuclear envelope
45
is the nuclear envelope completely broken down in pro metaphase
yes
46
what is a syntelic attachment
when 2 spindles from the same side attach the same chromosome twice (no tension)
47
whats a bi-orientated chromosome
both ends under tension of spindles
48
whats a mono orientated chromosome
no tension and connection is only on one side
49
whats the spindle equator also called
metaphase plate
50
what are the three microtubule groups
Astral MTs Chromosomal MTs Polar MTs
51
what do astral Mts do
they determine where division of the cell is going to happen/position spindle apparatus in cell
52
what do Chromosomal MTs do
moves chromosomes to poles
53
what do Polar MTs do
maintain spindle integrity
54
what microtubule group is not associated with chromosomes
polar MTs
55
whats responsible for some movement during metaphase
tubulin flux
56
what end do microtubules grow at
+
57
where does breakage of cohesion linkages occur
anaphase
58
what destroys cohesion linkages
separase
59
what inactivates separase prior to anaphase
securin
60
whats destroys securin so that sea parse can be activated
APC (anaphase porting complex)
61
whats does APC need to activate to ubiquitin Securin
cdc20
62
whats does APC need to activate to ubiquitin mitotic cyclins (cyclin B)
cdh-1
63
what destroys Cyclin B
after its been tagged by ubiquitin, it gets destroyed by proteosomes
64
what a key trigger for exit from mitosis and entry into G1 phase.
destruction of Cyclin B causing Cdk 1 inactivation
65
what would make the cell stay in the late stage of mitosis
no destruction of cyclin B (inhibiting the proteosome)
66
what is Anaphase A
movement of chromosomes towards the poles
67
what is Anaphase B
spindle poles moving in opposite directions
67
what is the driving force of Anaphase A
loss of tubulin subunits from kinetochore microtubules
68
whats the driving force of anaphase B
motor proteins (kinesin/dynein)
69
what anaphase separation is faster
anaphase B
70
what checks for misaligned chromosomes at metaphase/anaphase
the spindle assembly checkpoint (SAC)
71
what does the spindle assembly checkpoint (SAC) sense
loss or lack of tension
72
what is aneuploidy
abnormal number of chromosomes
73
whats the protein involved in the spindle assembly checkpoint (SAC)
Mad2
74
when do chromosomes disperse
telophase
75
what generates force to cleave cell
thin band of actin and myosin
76
what creates the cleavage furrow
actin and myosin
77
what is the ring contraction made of
myosin II

BMSC 220 (22 decks)

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