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Cell Cycle Flashcards

1
Q

what are the three main things cells have to do?

A

grow, segregate, and divide into two

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2
Q

what is the longest phase of the cell cycle?

A

interphase

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3
Q

what starts during anaphase

A

cytokinesis

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4
Q

depending on the type of cell determines what

A

how long the process is going to take

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5
Q

how many copies of DNA are in G1

A

one copy

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6
Q

how many copies of DNA are in S phase

A

1.1-1.9

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7
Q

what is happening in S phase

A

DNA replication

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8
Q

how many copies of DNA are in G2 phase

A

two copies

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9
Q

what is happening in G1 phase

A

it is getting ready for replication

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10
Q

how many times do cells replicate in S phase

A

once and only once

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11
Q

what is happening in G2 phase

A

getting ready for mitosis and makes a lot of microtubules to separate sister chromatids

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12
Q

what does START represent

A

the transition from G1 to S

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13
Q

START marks the

A

commitment to enter S phase

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14
Q

is the cell cycle a one or two way street

A

one way street

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15
Q

Flow cytometry determines what

A

the amount of DNA inside the cell and run it through an automated fluorescent microscope that forces cells to line up in a single file and pass through a laser which takes pics

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16
Q

wherever the arrest or stop is it will continue until it gets to…

A

that point and thats when it will arrest

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17
Q

examples of cells that are non-dividing

A

spinal cord, neurons, brain cells, smooth muscle cells of vascular system

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18
Q

what phase are cells non-dividing

A

G0

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19
Q

what are two major chromosomal events that occur in S phase and M phase

A

segregation and separation

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20
Q

what question is asked going from g1 to s phase

A

is the environment favorable?

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21
Q

what questions are asked going from g2 to mitosis

A

is all dna replicated?
is environment favorable?

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22
Q

what questions are asked in mitosis

A

are all chromosomes attached to the spindle?

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23
Q

what are two options for cell cycle checkpoints

A
  1. temporary cell cycle arrest
  2. permanent cell cycle arrest
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24
Q

how do the cell cycle checkpoints work?

A

cell cycle checkpoint work through CDKs

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25
what are CDKs
cyclin-dependent kinases
26
what do CDKs do
phosphorylate proteins that drive the cell cycle
27
CDKs must be activated by specific
cyclins
28
CDK levels are
constant
29
are CDKs activity constant
no just levels
30
what determines when the CDKs activate
the concentration of cyclins
31
cyclin binding moves what
an inhibitory protein loop (T-loop) out of the Cdk active site
32
what enzyme completes Cdk activation
CAK
33
CAK stands for
Cdk- activating kinase
34
what turns CDKs off
WEE1
35
WEE1 kinase is the only
phosphate that turns something off
36
what activated CDKs again
Cdc25 phosphatase
37
Cdc25 phosphatase does what
removes WEE1
38
what grabs on and prevents the CDKs from doing anything
p27
39
CDK Inhibitor proteins do what
inactivate cyclin-cdk complexes
40
what is a tumor supressor
p53
41
tumor suppressor genes do what
stop cell cycle from progressing
42
oncogenes act as
gas pedals that drive the cell cycle
43
DNA damage stimulates
p53
44
p53 activates the
transcription of CKI protein p21 that stops the cell cycle
45
what is loaded in G1 but not activated until S phase
pre-replicative complex preRC
46
what is always bound to the replication origin
ORC
47
what associated in G1
Cdc6
48
Cdc6 and ORC together along with Cdt1 do what
load the DNA replication helicase in an inactive form
49
S-Cdk phosphorylates helicase which is an
activator/ initiator protein
50
DDK phosphorylates
DNA helicase
51
phosphorylated DNA helicase initiates
DNA replication
52
what phosphorylated ORC, Cdc6, and Cdt1 to deactivate them
S-Cdk
53
when are ORC, Cdc6, and Cdt1 dephosphorylated
at the end of mitosis
54
why do we had to add cohesion proteins
so when dna replicated we know which strands of DNA go together
55
during replication cohesion protein deposited
along the length of the chromosome
56
cohesion rings encircle
both sister chromatids
57
what triggers condensation of replicated chromosomes and induces the assembly of the mitotic spindle, breaks down the nuclear envelope and rearranges the actin cytoskeleton
M-Cdk
58
what drives mitosis
M-Cdk
59
M-Cdk levels build up during
G2 phase
60
M-Cdk levels build up but is kept inactive by
Wee1
61
when cells enter M phase what is activated
Cdc25
62
Wee1 is suppressed and M-Cdk becomes
activated
63
by inhibiting Wee1 it does what
increases M-Cdk
64
what is M-Cdk tasked with
condensing our DNA into our sister chromatids
65
condensin is a
5-subunit protein that coils up DNA
66
condensin's activity is stimulated when it is
phosphorylated by M-Cdk
67
the cytoskeleton allows for
separation of duplicated chromosomes and the division of the cell
68
M-Cdk initiates
mitotic spindle assembly
69
microtubules originate from
centrosomes
70
microtubules pull
chromatids apart
71
the centrosomes or MTOCS are duplicated early in
S phase
72
the centrosomes duplicated in S phase form the
spindle poles
73
astral microtubules are found on
the backside and position the spindle pole at opposite ends of the cell
74
kinetochore microtubules interact with
sister chromatids
75
kinetochores orient
back to back
76
kinetochores reduce the chance that
both sister chromatids will become attached to one spindle pole
77
the arrangement of the kinetochore is called
bi-orientation
78
how many microtubules for each spindle pole attached to your sisters
1
79
what is responsible for anchoring the microtubule at the kinetochore
Ndc80
80
why is the formation of Ndc80 important
it forms a ring around the side of the microtubule and allows addition and loss at plus end
81
increased tension increases
microtubule binding affinity
82
the correct spindle attachment arrangement increases
tension at the kinetochore
83
astral microtubules position spindles poles
correctly
84
interpolar microtubules
interdigitate to provide stability and allow movement of the spindle poles
85
many motor proteins function in concert to align the spindle poles and the chromosomes on the
metaphase plate
86
APC/C is an
ubiquitin ligase
87
APC/C does what
gets rid of proteins we don't need and degrades M cyclins and S cyclins
88
what is activated by Cdc20 binding
APC/C
89
activated APC/C causes
sister chromatid separation by degrading securin
90
separase
a protease which cleaves cohesin
91
no tension means
no anaphase
92
chromosomes that is not attached to a spindle is going to
inhibit APC/C
93
relaxed kinetochore means
not bi-oriented
94
not bi-oriented means it
changes shape of kinetochore
95
a relaxed kinetochore alters shape of
Mad2 which activates it
96
Mad2 binds and inhibits
APC/C
97
what helps Mad2
BubR1
98
when we have tension what cant bind
Mad2 and BubR1
99
nondisjunction means
you do not have correct sister separation
100
more than 90 percent of tumors are
aneuploidy
101
aneuploidy means
abnormal chromosome number
102
if spindle assembly checkpoint does not operate properly during meiosis than gametes will be
aneuploid
103
down syndrome is from
nondisjunction during maternal meiosis I
104
klinefelter syndrome
two or more X chromosomes in males
105
unicellular organisms can afford to be
selfish
106
if damage is not repaired,
the cell will recommence the cell cycle
107
permanently arrested cells of multicellular organisms will undergo
apoptosis or programmed cell death

Cell Bio (5 decks)

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