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Chapter 18 Flashcards

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1
Q

3 basic steps of the cell cycle

A
  1. cell growth and chromosome duplication
  2. chromosome segregation
  3. cell division
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2
Q

M phase definition

A

period of the eukaryotic cell cycle during which the nucleus and cytoplasm divide to produce two daughter cells

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3
Q

interphase definition

A

long period of the cell cycle between one mitosis and the next
includes G1, S, and G2 phases

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4
Q

S phase definition

A

period during a eukaryotic cell cycle in which DNA is synthesized

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5
Q

G1 phase definition

A

Gap 1 phase of the eukaryotic cell cycle; falls between the end of cytokinesis and the start of DNA synthesis

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6
Q

G2 phase definition

A

Gap 2 phase of the eukaryotic cell cycle; falls between the end of DNA synthesis and the beginning of mitosis

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7
Q

three main transition points of cell-cycle control regulation

A

late G1 phase to confirm the environment is favorable (sufficient nutrients and specific signal molecules)
G2 to M phase to confirm that the DNA is undamaged and full replicated
midway through mitosis confirms the duplicated chromosomes are attached to the mitotic spindle correctly

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8
Q

start definition

A

important transition at the end of the G1 phase of the eukaryotic cell cycle; passage through this transition commits the cell to enter the cell cycle and continue to S phase

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9
Q

cell-cycle control system definition

A

network of regulatory proteins that govern the orderly progression of a eukaryotic cell through the stages of cell division

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10
Q

one of the most common ways by which cells switch the activity of a protein on and off

A

phosphorylation followed by dephosphorylation

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11
Q

phosphorylation reactions that control the cell cycle are carried out by _____

A

protein kinases

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12
Q

dephosphorylation reactions that control the cell cycle are carried out by ______

A

protein phosphatases

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13
Q

cyclin definition

A

regulatory protein whose concentration rises and falls at specific times during the eukaryotic cell cycle
help control progression from one stage of the cell cycle to the next by binding to cyclin-dependent protein kinases (Cdks)

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14
Q

Cdk (cyclin-dependent protein kinase) definition

A

enzyme that, when complexed with a regulatory cyclin protein, can trigger various events in the cell-division cycle by phosphorylating specific target proteins

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15
Q

When is cyclin concentrations high and low?

A

high during mitosis
low during interphase
vary in a cyclical fashion

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16
Q

M-cyclin definition

A

regulatory protein that binds to mitotic Cdk to form M-Cdk, the protein complex that triggers the M phase of the cell cycle

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17
Q

M-Cdk definition

A

protein complex that triggers the M phase of the cell cycle; consists of an M-cyclin plus a mitotic cyclin-dependent protein kinase (Cdk)

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18
Q

G1/S-cyclin definition

A

regulatory protein that helps to launch the S phase of the cell cycle

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19
Q

S-cyclin definition

A

regulatory protein that helps to launch the S phase of the cell cycle

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20
Q

G1/S-Cdk definition

A

protein complex whose activity triggers entry into S phase of the cell cycle; consists of a G1/S-cyclin plus a cyclin-dependent protein kinase (Cdk)

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21
Q

S-Cdk definition

A

protein complex whose activity initiates DNA replication; consists of an S-cyclin plus a cyclin-dependent protein kinase (Cdk)

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22
Q

G1-cyclin definition

A

regulatory protein that helps drive a cell through the first gap phase of the cell cycle and toward S phase

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23
Q

G1-Cdk definition

A

protein complex whose activity drives the cell during the first gap of the cell cycle; consists of a G1-cyclin plus a cyclin-dependent protein kinase (Cdk)

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24
Q

anaphase-promoting complex (APC/C) definition

A

a protein complex that triggers the separation of sister chromatids and orchestrates the carefully timed destruction of proteins that control progress through the cell cycle; the complex catalyzes the ubiquitylation of its targets

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25
how does the cyclin-Cdk complex becomes activated
Cdk must be dephosphorylated by a specific protein phosphatase
26
Cdk inhibitor protein definition
regulatory protein that blocks the assembly or activity of cyclin-Cdk complexes, delaying progression primarily through the G1 and S phases of the cell cycle
27
regulators that oppose Cdk
family of phosphatases called PP2A
28
control system uses ____ in late G1 phase to keep cells from entering the cell cycle
Cdk inhibitors
29
what control system occurs at the G2 to M transition
suppresses the activation of the M-Cdk by inhibiting the phosphatase required to activate the Cdk
30
what control system delays chromosome segregation in mitosis
inhibiting the activation of APC/C, preventing the degradation of M-cyclin
31
what must be inactivated for the cell to go from M phase to G1
S-Cdk M-Cdk
32
mammalian cells will multiply only if they are stimulated to do so by _____
mitogens
33
Mitogens act by switching on the cell signaling pathways that stimulate the synthesis of _____, ______, and ______
G1-cyclins G1/S-cyclins other proteins involved in DNA synthesis and chromosome duplication
34
what do retinoblastoma (Rb) proteins do
binds to particular transcription regulators and prevents them from turning on genes required for cell proliferation
35
p53 definition
transcription regulator that controls the cell's response to DNA damage, preventing the cell from entering S phase until the damage has been repaired or inducing the cell to commit suicide if the damage is too extensive
36
S-Cdk initiates _____ and blocks _______
DNA replication re-replication
37
what two proteins/protein complexes position the DNA helicases
origin recognition complex (ORC) Cdc6
38
how does S-Cdk prevent re-replication
phosphorylates Cdc6 and the ORC to inactivate the proteins
39
what needs to be done in the control cycle to move into M phase
inhibitory phosphates must be removed from M-Cdk by activating protein phosphatase (Cdc25)
40
what are the two main components of M phase
mitosis and cytokinesis
41
____ prepares the duplicated chromosomes for segregation and induces the assembly of the mitotic spindle
M-Cdk
42
M-Cdk complexes are reinforcing so they can indirectly...
turn on additional M-Cdk complexes
43
Trend of M-Cdk levels durong G2 and M phase
accumulate in G2 but aren't activated until end of G2
44
what controls the exit from mitosis
activated M-Cdk turns on APC/C which after a delay, directs the destruction of M-cyclin and inactivates M-Cdk
45
sister chromatid definition
copy of a chromosome, produced by DNA replication, that still remains bound to the other copy
46
cohesion definition
ring-shaped SMC protein complex that organizes interphase chromosomes into a long series of chromatin loops holds together the sister chromatids after DNA has been replicated
47
what is the term for mis-segregation that can lead to abnormal numbers of chromosomes
aneuploidy
48
condensin definition
ring-shaped SMC protein complex that compacts duplicated chromosomes for segregation by forming both loops and loops within loops
49
difference between cohesins and condensins
cohesins: encircle the sister chromatids, tying them together condensins: assemble along each sister chromatid, helping each of these double helices to coil up into a more compact form
50
the ________ divides the entire cell in two during cytokinesis
contractile ring
51
two critical events that must be completed before M phase begins
DNA must be fully replicated centrosome must be duplicated
52
centrosome definition
microtubule-organizing center that sits near the nucleus in an animal cell during the cell cycle, this structure duplicates to form the two poles of the mitotic spindle
53
aster definition
star-shaped array of microtubules emanating from a centrosome or from a pole of a mitotic spindle
54
mitotic spindle definition
array of microtubules and associated molecules that forms between the opposite poles of a eukaryotic cell during mitosis and pulls apart duplicated chromosome sets
55
spindle pole definition
centrosome from which microtubules radiate to form the mitotic spindle
56
what occurs before M phase
cell increases in size DNA of the chromosomes is replicated centrosome is duplicated
57
what occurs in prophase
sister chromatids condense mitotic spindle assembles between two centrosomes outside the nucleus
58
what occurs in prometaphase
breakdown of the nuclear envelope chromosomes attach to spindle microtubules via kinetochores
59
what occurs in metaphase
chromosomes are aligned at the equator of the spindle kinetochore microtubules attach to opposite poles of the spindle
60
what occurs in anaphase
sister chromatids separate and are pulled slowly towards the spindle pole
61
what occurs in telophase
two sets of chromosomes arrive at the poles of the spindle new nuclear envelope reassembles around each set contractile ring starts to form
62
what occurs in cytokinesis
cytoplasm is divided in two by a contractile ring
63
kinetochore definition
protein complex that assembles on the centromere of a condensed mitotic chromosome; the site to which spindle microtubules attach
64
a continuous balanced additional and loss of ____ subunits is required to maintain the metaphase spindle
tubulin
65
what protease destroys the cohesion linkage
seperase
66
before anaphase begins, seperase is held in an inactive state by an inhibitory protein called ____
securin
67
what happens in anaphase A
chromosomes move poleward kinetochore microtubules shorten
68
what happens in anaphase B
spindle poles are pushed and pulled apart
69
what happens at the spindle assembly checkpoint
kinetochores send a "stop" signal to block the activation of APC/C
70
contractile ring definition
structure made of actin and myosin filaments that forms a belt around a dividing cell, pinching it in two
71
phragmoplast definition
in a dividing plant cell, structure containing microtubules and membrane vesicles that guides the formation of a new cell wall
72
what do mitogens do
stimulate cell division, primarily by overcoming the intracellular braking mechanisms that block progression through the Start transition and entry into the cell cycle in late G1
73
what do growth factors do
stimulate cell growth by promoting the synthesis and inhibiting the degradation of proteins and other macromolecules
74
what do survival factors do
promote cell survival, largely by suppressing apoptosis
75
mitogens are secreted signal proteins that bind to _______
cell-surface receptors
76
most extracellular growth factors bind to ______ that activate intracellular signaling pathways
cell-surface receptors
77
capase definition
one of a family of proteases that, when activated, mediates the destruction of the cell by apoptosis
78
what are the two types of capases that work together to take a cell apart
initiator capases executioner capases
79
two important death-inducing proteins from the Bcl2 family
Bax Bak
80
cytochrome c molecule released from mitochondria activate ______
initiator capases and induce apoptosis by promoting the assembly of apoptosome

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