Cell Division and Cell Death Flashcards
(150 cards)
1
Q
S phase
A
DNA duplication, cell growth
2
Q
M phase
A
nuclear division (mitosis) + cytoplasmic division (cytokinesis)
3
Q
mitosis
A
chromosome segregation (microtubule based)
4
Q
cytokinesis
A
actin based
5
Q
interphase
A
S phase and the gap phases
6
Q
transition from metaphase to anaphase
A
abrupt change in the biochemical state of the cell
7
Q
Genetic dissection of cell-cycle pathways
A
normal vs. budding and the behaviors of temperature sensitive Cdc mutants
8
Q
biochemical dissection of cell-cycle pathways
A
- large egg size
- in vitro recapitulation
9
Q
Common experimental tools for analyzing cell-cycle
A
- BrDU (thymidine analog) labeling
2. FACS profile of DNA content
10
Q
BrdU labeling
A
labels newly synthesized DNA which targets cells in the S phase
11
Q
FACS profile of DNA content
A
relative # of DNA in the cell tells you what phase, number of cells tells you how long the phase is
- the fluorescent dye labels DNA in cells
12
Q
cell-cycle control system
A
triggers the major events of the cell cycle
13
Q
checkpoints
A
assure that cell cycle continues without defects
14
Q
CDK (cyclin dependent kinase)
A
control components of cell-cycle
activity regulated by cyclins
Cyclins undergo cycles of synthesis and degradation during cell cycle
15
Q
Four types of cyclins
A
- G1/S
- S
- M
- G1
16
Q
restriction point (first checkpoint) in late G1
A
the cell commits to cell-cycle entry and chromosome duplication
17
Q
G2/M checkpoint
A
control system triggers early mitotic events that lead to chromosome alignment on the spindle in metaphase
18
Q
metaphase-to-anaphase transition
A
control system stimulates sister-chromatid separation, leading to the completion of mitosis and cytokinesis
19
Q
levels of Cdk proteins
A
constantduring cell cycle
20
Q
levels of cyclins
A
cyclical
21
Q
G1/S cyclins
A
activate Cdks in late G1; help trigger progression through start resulting in a commitment to cell-cycle entry. levels fall in S phase
22
Q
S-cyclins
A
bind Cdks soon after progression through Start and help stimulate chromosome duplication. S-cyclin levels remain elevated until mitosis, and these cyclins also contribute to the control of some early mitotic events
23
Q
M-cyclins
A
activate Cdks that stimulate entry into mitosis at the G2/M checkpoint. Mechanisms that we discuss later destroy M-cyclins in mid-mitosis
24
Q
G1 cyclins
A
help govern activities of the g1/S cyclins, which control progression through Start in late G1
25
inhibitory phosphorylation and Cdk inhibitory proteins (CKIs) can
suppress Cdk activity
26
CDK activity is positively regulated by
cyclins and CAK (Cdk activating kinase)
27
CDK activity is negatively regulated by
inhibitory phosphorylation and CKI (Cdk inhibitors)
28
What controls the cyclins and the CKIs?
proteolysis
29
APC
anaphase promoting complex (a ubiquitin ligase)
30
What does APC do?
catalyzes ubiquitylation of securin and S/M cyclins
31
p27 degradation by
phosphorylation
32
metaphase-anaphase transition controlled by
protein destruction - proteolysis
33
p27
CKI, controls the cell cycle progression at G1
34
Cdk-activating kinase (CAK)
phosphorylates an activating site in Cdks
35
Wee1 kinase
phosphorylates inhibitory sites in Cdks; primarily involved in suppressing Cdk1 activity before mitosis
36
Cdc25 phosphatase
removes inhibitory phosphates from Cdks; three family members (Cdc25A, B, C) in mammals; primarily involved in controlled Cdk1 actiation at the onset of mitosis
37
Sic1 (budding yeast)
CI, suppresses Cdk1 activity in G1; phosphorylation by Cdk1 at the end of G1 triggers its destruction
38
p27 (in mammals)
CKI, suppresses G1/S-Cdk and S-Cdk activities in G1; helps cells withdraw from cell cycle when they terminally differentiate; phosphorylation by Cdk2 triggers its ubiquitylation by SCF
39
p21 (mammals)
suppresses G1/S-Cdk and S-Cdk activities following DNA damage
40
p16(mammals)
suppresses G1-Cdk activity in G1; frequently inactivated in cancer
41
APC/C
catalyzes ubiquitylation of regulatory proteins involved primarily in exit from mitosis, including securin and S- and M-cyclins; regulated by association with activating subunits
42
Cdc20
APC/C-activating subunit in all cells; triggers initial activation of APC/C at metaphase-to-anaphase transition; stimulated by M-Cdk activity
43
Cdh1
APC/C-activating subunit that maintains APC/C activity after anaphase and throughout G1; inhibited by Cdk activity
44
SCF
catalyzes ubiquitylation of regulatory proteins involved in G1 control, including some CKIs (Sic1 in budding yeast, p27 in mammals); phosphorylation of target protein usually required for this activity
45
Cell-Cycle control system functions as
a network of biochemical switches
46
gamma tubulin
nucleates MT at MTOC
47
alpha tubulin binds
GTP irreversibly (cant hydrolyze)
48
beta tubulin binds
GTP, hydrolyzes
49
(+) end vs (-) end
+ is beta
50
How many protofilaments make the structure?
13
51
microtubule assembly principle -
similar to that of actin
52
which end is faster assembly
(+) end twice as fast
53
tubulin assembly dependent on
temp
low - dimer
high - polymer
54
Cc
critical concentration - below this polymerization does not take place
55
how to bypass lag phase
add nucleus
56
treadmilling..
at Cc+
57
Assembly of protofilaments
1. linear assembly of aB dimers
2. lateral association into protofilament (stabilization)
3. assembly at ends
58
GTP cap of protofilaments
Btubulin adds at GTP before being hydrolyzes
59
catastrophe
shrinking stage
60
rescue
elongation stage
61
dynamic instability is...
an intrinsic property of microtubules
62
determinants of dynamic instability
[tubulin]
| nucleotide status at end
63
microtubule-associated proteins (MAPs)
influence the assembly and stability of microtubules
64
Two groups of MAPs
1. stabilizes microtubules
| 2. destabilizes
65
domains fo stabilizing MAPs
1. basic microtubule binding domain
| 2. acidic projection domain
66
Popular microtubule drugs
1. Nocodazole (depol)
2. Colchicine (depol)
3. Taxol (stabilizes; anti cancer drug)
67
two families of motor proteins
kinesins and dyneins
68
microtubule trasnport is...
bidirectional
| Therfore, two kinds of motor proteins
69
Vesicle attachment is..
ATP dependent
70
translocation is...
ATP hydrolysis dependent
71
what is required for vesicle attachment/movement?
cytosolic fator
72
kinesin
(+) end directed microtubule motor protein
| 10 different kinds
73
Head of kinesin binds to
+MT (Btubulin), ATP
74
Tail of kinesin binds to
cargo (vesicle)
75
dyneins
-end directed motors for microtubules
| can't mediate cargo transport by itself - required dynactin
76
dynactin
helper protein for dyneins
| binds to MT vesicles
77
The mitotic apparatus is...
a microtubule machine for separating chromosomes
78
mitotic apparatus parts
mitotic spindle and pair of asters
79
mitotic spindle
bilaterallay symmetric bundle of microtubules and associated proteins with the overall shape of a football
80
aster
radial array of microtubules at each pole of the spindle
81
duplicated centrosomes align and begin sep in...
prophase
82
centrosome movement during mitosis by..
kinesin and dynein
83
Attachment of microtubule to the sister chromatids by
kinetochore complex
84
Capture of chromosome by...
microtubules
85
random capture by...
alternate growing and shrinking of microtubules
86
What follows the random capture at kinetochore complex?
chromosome sliding toward the +end of MT using kinetochore associated +end motor
87
Stabilization of chromosome at cell equator
1. Kinetochore dynein and kinesin at pole pull chromosome toward the pole
2. chromokinesin push chromosome away from pole
3. treadmilling of tubulin subunits stabilizes the length of the spindle MT
88
Early anaphase
depolymerization of MT at +end (as revealed by bleaching experiment)
89
anaphase chromosomes ... and the spindle...
separate, elongates
90
observation from bleaching experiment
distance between bleach and pole remains same (no depol at -end)
distance btw bleach and +end decrease (depol at +end)
91
late anaphase
spindle elongation and movement at poles
92
outward movement of centrioles by...
dynein attached to cell membrane
93
outward movement of centriole...
by spindle kinetochores
94
further elongation of spindle...
by MT polymerization
95
Rho signaling promotes...during cytokinesis
acto-myosin contraction
96
local activation of RhoA triggers
assembly and contraction of contractile ring
97
S-cyclin-CDK initiates DNA...
only ONCE/CYCLE
98
Assembly of pre-RC is...
inhibited by CDK and facilitated by APC in early G1
99
How does DNA damage block G1 to S progression?
by act p53 and stimulating p21 (CKI) transcription
100
p53
major tumor-suppresor
101
mitogen
extracellular signal molecule that stimulates cells to proliferate
EGF, PDGF, FGF
102
mitogen-activated protein kinase
MAP-kinase; protein kinase at the end of a three-component signaling module involved in relaying signals from the plasma membrane to the nucleus
103
without mitogen
cells in G1 or G0 (exit cell cycle)
104
mitogens stimulate
G1 to S phase progression
increase in G1/S cyclins
increase in S-cyclins
decrease in CKI
105
the most vital checkpoint
G1 to S
106
anaphase promoting complex (APC) controls
degradation of mitotic cyclins and exit from mitosis
107
S phase entry
- mitogens stim MAPK activation
- immediate early gen (fos, Jun) exp
- turn on Myc exp ->cyclin D exp
- activate CDK4/6 -> Rb phos
- > S-phase gene transcription by E2F
108
myc
oncogene
109
Rb
tumor suppressor
110
Growth and division
usually coordinated
| EXCEPT: muscle cells, frog eggs
111
What limits cell proliferation?
telomere
112
Abnormal proliferation cues
cell cycle arrest/apoptosis
113
Cell cycle arrest or apoptosis induced by
excessive stimulation of mitogenic pathways
114
unintentional cell death
necrosis
115
intentional cell death
apoptosis
116
autophagy
cell eating itself
117
what eats apoptotic cells?
macrophages or neutrophils
118
apoptotic cells are...
biochemically recognizable
119
biochemical signature of apoptotic cells
1. phosphatidylserine flip from inner to outer (signal to macrophages)
2. DNA fragmentation
120
TUNEL
dUTP nick end labeling (TUNEL) is a method for detecting DNA fragmentation by labeling the terminal end of nucleic acids.
121
annexin V
detects phosphatidylserine flip
122
caspase
proteases; mediators of apoptosis
C-cysteine
ASP - aspartic acid
ASE - cuts
123
cleavage of caspase
into active form by another caspase
124
Types of caspases
inflammation - 1,4,5
apoptosis:
initiator - 2,8,9,10
executioner - 3,6,7
125
extrinsic pathway
extracellular to apoptosis
| can invoke intrinsic for greater response
126
intrinsic pathway
intracellular signal to apoptosis
127
apoptosis depends on
intracellular proteolytic cascade mediated by caspases
128
E2F protein
gene regulatory protein that switches on many genes that encode proteins required for entry into the S phase of the cell cycle
129
death receptor
transmembrane receptor protein that can signal the cell to undergo apoptosis when it binds its extracellular ligand
-extrinsic pathway
130
Fas ligand
binds to Fas death receptor to assemble DISC
131
DISC
death-inducing signaling complex
| Fas death receptors, intracellular adaptor proteins and initiator procaspases
132
intrinsic pathway of apoptosis
depends on the release into the cytosol of mitochondrial proteins that normally reside in the intermembrane space of these organelles.
- involves cytochrome c from mitochondria
133
Release of cytochrome C activates
caspase C chain through APAF (apoptotic protease activating factor-1)
134
apoptosome
wheel like heptamer of Apaf1
recruit initiator procaspase proteins
then activate downstream executioner procaspases to induce apoptosis
135
BCL2 family proteins
regulators of apoptosis
136
How does extrinsic promote intrinsic?
converts one of the Bcl2 proteins and cuts to truncated always active form...
137
IAPs
inhibit caspases
138
inhibitors of apoptosis (IAPs)
intracellular protein - inhibitors of apoptosis
139
anti-IAPs
produced in response to various apoptotic signals
| IAP-binding motif
140
anti-IAPs are released from
mitochondrial intermembrane space when the intrinsic pathway of apoptosis is activated blocking IAPs in the cytosol and thereby promoting apoptosis
141
survival factor
extracellular signal that promotes cell survival by inhibiting apoptosis
142
Hid
anti-IAP protein
143
phosphorylation of Hid
survival factor activates MAP-kinase
| apoptosis blocked
144
Akt kinase
serine/threonine protein kinase
145
three ways that extracellular survival factors can inhibit apoptosis
A. increased production of anti-apoptotic Bcl2 protein
B. inactivation of pro-apoptotic BH3-only Bcl2 protein
C. inactivation of anti-IAPs
146
activation of AKT kinase
activates Bcl2 and inactivates Bad
| apoptosis blocked
147
stimulation of transcription of genes that encode anti-apop Bcl2
apoptosis blocked
148
too much apoptosis
tissue damage - heart attacks, strokes
149
too little apoptosis
accumulation of cells - autoimmune
| tumors
150
Bcl2 gene
lymphocyte cancer
