cell cycle Flashcards
(100 cards)
1
Q
G0
A
cells are quiescent, can be reversed
2
Q
Interphase?
A
G1 S G2
3
Q
G1
A
first gap phase; period between birth of daughter cell and onset of DNA synthesis. cells grow in size and make critical decisions about whether to divide, become quiescent and differentiate.
4
Q
S
A
DNA replication and centrosome duplication.
5
Q
G2
A
Second gap phase. 3-5hrs. cells prepares for mitosis.
6
Q
M
A
prophase prometaphase(nuclear envelope breakdwon) metaphase anaphase telophase(nuclear envelope reform)
7
Q
cytokinesis
A
reformation of interphase microtubule array, contractile ring forms cleavage furrow
8
Q
Anaphase A
A
chromosome movement to poles
9
Q
Anaphase b
A
spindle pole separation
10
Q
duplication of centrosome is what kind of manner?
A
semi-conservative
11
Q
centrosomes, lilke chromosome duplication, they occur ____and only ___ per cell cycle
A
ONCE
12
Q
incorrect number of centrosomes leads to what?
A
defects in spindle assembly and errors in chromosome segregation, resulting in aneuploidy
13
Q
Centrosomes are “____center”
A
self center
14
Q
two centrosomes move apart along nuclear envelope and what increases?
A
g-TuRC
15
Q
Increases of g-TuRC increases what?
A
increases nucleation of MTs
16
Q
what is called increased nucleation of MTs?
A
centrosome maturation
17
Q
this link sister chromatids
A
cohesins
18
Q
cohesins contain 4 subunits?
A
Smc 1/3 and Scc 1/3
19
Q
Smc stands for?
A
structural maintenance of chromosomes
coiled/coil proteins with ATPase domain at one end
20
Q
what connect ATPase head domains that forms circle enclosing sister chromatids?
A
Scc1 and 3
21
Q
cohesin - sister chromatids complex is disrupted when?
A
metaphase-anaphase transition
22
Q
when does cohesins hold sister chromatids?
A
after S phase
23
Q
structure of cohesin
A
multiprotein complexes, primarily SMC1/3 linked together by Kleisin
when smc1/3 depleted, sister chromatids didn’t associte properly
24
Q
cohesin mutant (yeast) have what kind of error?
A
errors in chromatid segregation
25
during condensation(late prophase) this phosphorylate cohesins and they dissociate from chromatids
kinases activated by MPF
26
M phase
spindle formation
27
mitotic spindle is what based?
MT based to separating sister chromatids
28
3 classes of MTs (mitotic spindles)
1. astral MT (from the pole to cell cortex)
2. kinetochore MT (spindle pole to chromosome)
3. polar MTs (anti parallel)
29
Embroynic cell cycle lacks which steps?
G1 / G2
| so it's S --> M
30
egg cytoplasm has what?
tubulin, ATP and cytoplasmic proteins necessary for mitosis
31
sperm nuclei contributes what?
centrosome, DNA, and nuclear protein
32
In interphase, extract contains what kind of MT?
a few long MTs
33
at M phase, MT converted into what?
larger number of shorter and more dynamic MTs around each centrosome.
34
during prophase (and prometaphase) what happened to MT?
half life of MTs decreases dramatically
35
increase in MT instability with ability of centrosome to nucleate MTs results what?
very dense and dynamic array of MTs
36
which phase has lowest catatrophes/min in MT?
interphase extract
37
which phase has highest catastrophs/min in MT?
mitotic extract without MAP
38
existence of MAP does what to MT?
higher the MAP, more stability
39
depleted MAP215 does what?
increase catastrophy ( decrease stability)
40
what is the catastrophe factor
kinesin 13
41
what promotes MT stability?
XMAP215 (MAP)
42
what proteins directly affect MT dynamics?
kinesin13 and XMAP215
43
specialized protein complex associated with centrosome
kinetochore
44
kinetochore protein is visualized by ABs from what?
patients with lupus
45
kinetochore proteins act to capture what ends of spindle MT?
(+) END
46
how kinetochore is constructed?
back to back orientation (prevents MTs from same pole attachign to kinetochore on both sister chromatids)
47
spindle MTs attach to the chromosomes at where?
Kinetochore
48
yeast kinetochores attached to how many MT?
ONE
49
human kinetochores attached to how many MT?
about 30
50
plant kinetochores attached to how many MT?
about 100
51
what are the components of kinetochore?
inner and outer
52
what ends are embedded in MT attachment?
(+) end at outer
53
what is Ran?
Ras-related Nuclear antigen, part of nuclear import/export machinary
54
Ran-GEF?
activates Ran in the nucleus
55
Ran-GAP is where?
distributed evenly throught out cytoplasm.
| REMEMBER: no nuclear membrane during M
56
which Ran (GDP OR GTP) concentration is high near chromosome?
Ran GTP
57
what induces release of MT stabilizing factors?
Ran GRP
58
what results in selective stabilization of MT near chromosome?
high conc. of Ran-GRP near chromosome and low elsewhere. This biases gorwth of MT towards kinetochore!
59
what creates tension across chromosome?
Bi-orienation. increased tension stabilizes MT attachment
60
what marks kinetochores assemble at chromosome region?
H3 Histone variant, CENP-A
61
kinetochore assembly consists of how many protein?
40 protein ( conserved from yeast to man)
62
this long and flexible complex linking (+) end of MT to inner kinetochore
Ndc-80 complex
63
Ndc function is controlled by?
proteins in the chromosomal passenger complex (CPC)
64
early mitosis, CPC is located where?
inner centromeric region
65
CPC contains what?
kinase "Aurora-B"
66
Aurora - B ?
phosphorylates several kinetochore components in centromeric region, (Ndc-80, pNdc-80 has weak association MT)
67
what is associated with outer kinetochore and removes phosphates from Ndc-80
PP1 (protein phosphatase 1)
68
Ndc-80 is phosporalyed by?
Aurora b
69
Ndc-80 is dephosphorylated by?
PP1
70
Bi-orientaion pulls both kinetochore (away or toward) from CPC?
away
71
pulling Ndc-80 does what?
increase spacing b/t inner and outer kinetochore plates
72
increased space b/t inner and outer kinetochore plates does what?
aurora b no longer phosphorylat, thus (unphosphorylated) has strong attachment to (+) end of MT
73
What helps orient chromosome?
motor proteins
74
kinetochore moves toward spindle pole, iniwhat dependent manner?
dynein dependent manner
75
chromosome arm moves away from pole, this indicates..?
indicating (+) end directed motor associated with arm
76
how do MT find kinetochore?
search and capture mechanism.
77
What are the names for anaphase A?
CENP-E/kinesin 7(growth)
kinesin 4 ( pulls arms toward center)
kinesin 13( depolymerzing + end)
dynein/dynatic ( strong pulling towards pole)
78
anaphase begins when cohesins at kinetochore are digested by what enzyme?
separase
79
what is anaphase A?
separation of chromatids without separation of spindle poles
80
what does kinesin13?
deolymerizes both + and - ends, and loss of GTP cap provides energy for movement.
81
at anaphase, CPC remains where?
midzone as chromosome are pulled apart, CPC asosciated with polar MT
82
what complex joins CPC?
Centralspindlin complex, contains (+) end directed kinesin motor protein
83
during anaphase B?
centralspindin recruits Cyk4 and exchange factor for RhoA.
84
RhoA-GTP activates what?
formin, which nucleates assembly of actin filaments in contractile ring
85
polar MT have what capabiility?
furrow inducing capability
86
RhoA?
small G protein which regulated actin polymerization (control formin activity) and myosin 2 activity (by "p" myosin light chain)
87
what is rhoA regulatory protein?
Cyk4
| rhoA forms ring in cell cortex, but cyk4 localized to equatorial plane of cell, associated with MT
88
what is anaphase B?
separation of chromatids with concurrent separation of spindle poles
89
what is involved in anaphase B?
kinesin 5 ( bipolar kinesin that associated with overlapping polar MT) +end of MT
dynein/dynactin complex (attaced to PM)
Aster Mt (with +end)
Dynein (-) end
90
what is the finals step of the cell cycle?
cytokinesis
91
what is the first visible manifestation of cytokinesis?
cleavage furrow (occurs at the same time as telophase - nuclear envelope reassembly and chromain decondensation)
92
contractile ring is what based structure?
actin based
93
assembly of actin filamenhts is initiated by what?
formin
94
as cells enter mitosis, actin and myosin2 accumulate where?
midpoint as sister chromatids separate in anaphase, and form contractile ring
95
anaphase spindle orients what?
cleavage plane
96
how is site of cleavage furrow determined? 3 models
1. astral MT carry factor to promotes actin/myosin contratility
2. molar MT generate signal
3. astral MT carry factor that inhibits actin/myosin contractility at cortex
97
Astral MT determine cleavage plane?
put glass bead/furrow forms only on one side of cell,
98
Astral MT inhibit conractility?
in worms, treatments that block astral MTs results in actin myosin contractility throughout cell cortex.
99
Polar MT have furrow inducing capability?
proteins that induce furrow formation are localized to overlapping interpolar MT
100
active RhoA (GTP) does two, what are they?
formin --> actin filament
| rho activated kinase --> myosin2 activation
