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Molecular cell bio > F lec 16 > Flashcards

F lec 16 Flashcards

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1
Q

_____________ _____________ ______________ marks the beginning of prometaphase

A

nuclear envelope breakdown (prophase –> prometaphase)

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2
Q

in interphase, chromosome are _________________

A

decondensed (allows for transcription and DNA replication at S-phase)

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3
Q

in interphase, chromosomes are decondensed, which allowed for ________________ and ______ ________________ at S-phase

A

transcription, DNA replication

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4
Q

for proper chromosome segregation in anaphase, chromosomes must first be packaged into a highly ________________ form

A

condensed

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5
Q

for proper chromosome _________________, chromosomes must first be packaged into a highly condensed form

A

segregation

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6
Q

the ________________ complex promotes chromosome condensation in prophase - may act as a ring connecting 2 parts of a chromosome

A

condensin

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7
Q

the condensin complex promotes chromosome condensation in prophase - may act as a __________ connecting 2 parts of a chromosome

A

ring

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8
Q

condensin complex is activated when it is phosphorylated by _________

A

CDK1

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9
Q

______ is the key initiating event of mitosis, and allows cytoplasmic proteins access to the nucleus and nuclear proteins access to the mitotic spindle

A

NEB

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10
Q

NEB allows ___________________ from the mitotic spindle access to the _________________

A

microtubules, kinetochore

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11
Q

intermediate filament proteins that support the nuclear envelope

A

nuclear lamins

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12
Q

NEB is triggered by ________ phosphorylation of many targets including the nuclear pore complex and nuclear lamins

A

CDK

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13
Q

NEB is triggered by CDK _________________ of many targets including the nuclear pore complex and nuclear lamins

A

phosphorylation

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14
Q

NEB is triggered by CDK phosphorylation of many targets including the ____________ __________ _____________ and _______________ _________________

A

nuclear pore complex, nuclear lamins

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15
Q

NEB occurs when __________ activity reaches its maximum level

A

CDK1

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16
Q

the negative end of a microtubule is at the __________________

A

centrosome

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17
Q

the _______________ end of a microtubule is at the centrosome

A

negative

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18
Q

the _______________ end of a microtubule radiates out (from the centrosome)

A

positive

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19
Q

the positive end of a microtubule ______________ ___________

A

radiates out (from the centrosome)

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20
Q

all 3 types of microtubules start out as ______________ microtubules before they differentiate

A

astral

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21
Q

microtubules that grow and shrink rapidly in prometaphase and capture kinetochores on chromosome to become kinetochore microtubules

A

astral microtubules

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22
Q

when an astral microtubule captures a kinetochore, it becomes a __________________ _________________

A

kinetochore microtubule

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23
Q

microtubules from either pole that interact in the spindle midzone, stabilizing the bipolar spindle - the sliding of interpolar microtubules then allows pole separation in anaphase and these establish the site of cytokinesis

A

interpolar microtubules

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24
Q

interpolar microtubules come from either pole and interact in the _______________ _________________

A

spindle midzone

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25
Q

the _______________ of ___________________ microtubules allows pole separation in anaphase

A

sliding, interpolar

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26
Q

interpolar microtubules establish the site of _______________

A

cytokinesis

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27
Q

microtubules with plus ends that associate with kinetochores at the centromeres of chromosomes - can shrink and grow by polymerization or depolymerization at plus end while still holding onto the kinetochores

A

kinetochore microtubules

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28
Q

kinetochore microtubules polymerize and depolymerize at the ________ end in order to grow or shrink

A

plus (+, positive, however the fck you wanna say it)

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29
Q

replicated sister chromatids are held together by __________________

A

cohesins

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30
Q

replicated _____________ _____________ are held together by cohesins

A

sister chromatids

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31
Q

the ________________ is the multiprotein complex that assembles at the centromere of both sister chromatids for each chromosome

A

kinetochore

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32
Q

the kinetochore is the multiprotein complex that assembles at the ________________ of both sister chromatids for each chromosome

A

centromere

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33
Q

the separation of sister chromatids requires the loss of ________________ and depolymerization of kinetochore microtubules

A

cohesins

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34
Q

the __________ ________________ binds to the centromeric regions of the chromosomes

A

inner kinetochore

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35
Q

the ____________ ________________ is thought of as acting like a collar around the kinetochore microtubule

A

outer kinetochore

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36
Q

the subunits of the microtubule that can be added or removed are composed of _______________ (addition or removal causes the microtubule to grow or shrink)

A

tubulin

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37
Q

kinetochore attachment leads to the _____________________ of kinetochore microtubules from the plus ends

A

depolymerization (shrinking to pull apart)

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38
Q

during depolymerization of kinetochore microtubules, the ______________ ________________ remains attached

A

outer kinetochore

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39
Q

_________________ is what pulls kinetochores and associated microtubules to poles

A

depolymerization

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40
Q

in ___________________, kinetochore attachments are unstable

A

prometaphase

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41
Q

in prometaphase, kinetochore attachments are ______________

A

unstable (so they frequently lose their attachment and must reattach)

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42
Q

due to unstable kinetochore attachment, microtubules often lose their attachments to the kinetochore and need to reattach- but in the meantime the other pole might grab it making it look like chromosomes move ______________ ________ ____________ in prometaphase

A

back and forth

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43
Q

in _________________, due to unstable microtubule-kinetochore attachment chromosomes appear to move back and forth

A

prometaphase

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44
Q

when a chromosome is successfully captured by microtubules from both poles, kinetochore attachments are ____________________

A

stabilized

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45
Q

proper chromosome segregation requires capture of both sister chromatids by microtubules from opposite poles, known as ____________ _______________

A

amphitelic attachment

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46
Q

incorrect microtubule attachment where only one microtubule attaches to one of the sister chromatids

A

monotelic attachment

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47
Q

incorrect microtubule attachment where both kinetochores attached to microtubules coming from the same pole

A

syntelic

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48
Q

incorrect microtubule attachment where only one kinetochore is attached to 2 microtubules from opposite poles

A

merotelic

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49
Q

______________ _____ ____________ is the enzyme that is responsible for why kinetochore attachments are unstable in prometaphase

A

aurora B kinase

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50
Q

aurora B kinase is inactivated by ___________ ____________ that occurs when amphitelic attachment occurs and pulls the chromatids in opposite directions to create the condition needed to inactive aurora B kinase

A

physical tension

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51
Q

if _____________ _____ _____________ is missing, then monotelic, syntelic, and merotelic attachments are not destablized and these chromosomes are pulled to one pole (improper segregation)

A

aurora B kinase

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52
Q

aurora B kinase is localized to the ______________ and phosphorylates kinetochore components leading them to bind microtubules less efficiently

A

kinetochore

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53
Q

aurora B kinase is localized to the kinetochore and ____________________ kinetochore components leading them to bind microtubules less efficiently

A

phosphorylates

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54
Q

once all of the kinetochores achieve an amphitelic attachment and aurora B kinase is inactivated and the kinetochore attachments are stabilized, the ______________ _________ must be broken for pulling force to initiate anaphase

A

cohesin rings

55
Q

the completion of anaphase requires the inactivation of CDK1 by destroying _____________

A

cyclin B

56
Q

the completion of anaphase requires the inactivation of ___________ by destroying cyclin B

A

CDK1

57
Q

in _______________, chromosomes remain at the midzone because they are attached to eachother via cohesins

A

metaphase

58
Q

in metaphase, chromosomes remain at the ______________ because they are attached to eachother via cohesins

A

midzone

59
Q

in metaphase, chromosomes remain at the midzone because they are attached to eachother via _____________

A

cohesins

60
Q

anaphase occurs when _____________ bonds are broken

A

cohesin

61
Q

the breaking of cohesins to separate sister chromatids relies on the destruction of the protein _______________

A

securin

62
Q

in anaphase the mitotic spindle pulls chromatids to spindle poles, which depends on the destruction of _______________ _____

A

cyclin B

63
Q

the destruction of both securin to initiate anaphase and cyclin B to complete anaphase depends on a ______________ _____________ called the Anaphase Promoting Complex/ Cyclosome (APC/C)

A

ubiquitin ligase

64
Q

the destruction of both securin to initiate anaphase and cyclin B to complete anaphase depends on a ubiquitin ligase called the ______________ ________________ ______________ ______________

A

Anaphase promoting complex/cyclosome (APC/C)

65
Q

Experiment to determine whether there is a specific sequence that allows cyclin B to be targeted for degradation:

A

JUST READ IT

66
Q

if the 90 aa sequence at the N-terminus of cyclin B is deleted, the protein becomes stable and mitosis arrests in ___________ ___________

A

early anaphase (meaning it cannot complete anaphase until cycB is degraded)

67
Q

Experiment showing that NEB is caused by cycB:

A

JUST READ IT

68
Q

if you were to add both delta90-cycB and full length cycB, the extracts have an ___________ _____________ ____________ still because not all the cycBs are degraded

A

early anaphase arrest

69
Q

delta90-cycB is still able to induce entry into metaphase in xenopus extracts or eggs, but these extracts or eggs arrest in _________________

A

metaphase ( /early anaphase as previously stated)

70
Q

the CDK1-cycB complex is known as _____________ _____________ _______________ and is necessary for entry into mitosis

A

Maturation Promoting Factor (MPF)

71
Q

_________ activates the cyclin destruction machinery

A

MPF (CDK1-cycB)

72
Q

once cyclin destruction machinery is active, it destroys cyclin and _________ is no longer active (negative feedback)

A

MPF

73
Q

destruction of cycB is necessary for ___________ _________ _____________ and inactivation of the cyclin destruction machinery

A

exit from mitosis

74
Q

to determine the specific sequence within the 90 aa region necessary on the cyclin they looked for ______________ ______________ within this region amongst cyclins from different species

A

conserved motifs

75
Q

after looking for conserved motifs in the 90 aa region on the cycB protein, they found a ____(#) aa sequence conserved that goes __________________, and is called the ________________ _______________

A

9, RxxLxxxxN, destruction box

76
Q

proving that the destruction box is ____________________:

A

sufficient

77
Q

proving that the destruction box is __________________:

A

necessary

78
Q

means that having this sequence without the rest of the region is enough to cause destruction

A

sufficient

79
Q

means that without the sequence there the destruction wont happen at all

A

necessary

80
Q

the destruction box was found to be both _______________ and ________________ for the destruction of cyclin B

A

sufficient, necessary

81
Q

experiment to determine that the destruction box is sufficient to cause destruction of the protein:

A

protein A

82
Q

if they added the 90 aa cycB fused with protein A to an __________________ extract, it would not be degraded

A

interphase

83
Q

experiment to determine that the destruction box is necessary to cause destruction of the protein:

A

mutate

84
Q

during experimentation, it was found that mutating a single amino acid in the destruction box ________ makes protein A fused to the destruction box stable again

A

R42C

85
Q

as the protein A was being degraded when tagged with the destruction box, why was there a ladder of higher molecular weight form that gets detected?

A

polyubiquitination (of protein A to target it for destruction, every band is +1 ubiquitin)

86
Q

the proteins __________,__________, __________ were identified as being required for anaphase progression and destruction of B-type cyclins by ubiquitination

A

cdc16, cdc23, cdc27

87
Q

the proteins cdc16, cdc23, and cdc27 were identified as being required for _____________ progression and destruction of B-type cyclins by ubiquitination

A

anaphase

88
Q

the proteins cdc16, cdc23, and cdc27 were identified as being required for anaphase progression and destruction of _______________ by ubiquitination

A

cyclin B

89
Q

the proteins cdc16, cdc23, and cdc27 were identified as being required for anaphase progression and destruction of B-type cyclins by _________________

A

ubiquitination

90
Q

__________ is an active kinase that phosphorylates the APC and this phosphorylation is necessary for the activity of the APC cdc20

A

CDK1

91
Q

the subunit on the APC that actually recognizes the destruction box on the cyclin

A

cdc20

92
Q

the interaction whereby the CDK1 complex activates the APC cdc20 subunit to deactivate the CDK1 complex that activates it can be described as _______________ _____________

A

negative feedback

93
Q

what did Aiden Mitrevski call the erectile dysfunction of protein signaling pathways?

A

when the destruction box on cycB is lost so APC cdc20 keeps getting higher and higher signaling to activate but cant actually do its job because there is no destruction box to target with ubiquitin

94
Q

the destruction of cyclin B (resulting in loss of CDK1 activity) is necessary for the movement of sister chromatids to poles in ___________ ______________

A

late anaphase

95
Q

other than destroying cyclin B, it is also important to destroy ________________ (which is a target of the APC) because destroying this protein is necessary for cohesin removal and separation of sister chromatids at the onset of anaphase

A

securin

96
Q

________________ keep sister chromatids together until anaphase of mitosis

A

cohesins

97
Q

cohesin complexes are assembled in _____-___________

A

S-phase

98
Q

_______________ requires cohesin removal

A

anaphase

99
Q

the segregation of sister chromatids in anaphase depends on the breaking of cohesin complexes by _______ __________________

A

SCC1 cleavage

100
Q

in defective APC mutants:

A

JUST READ IT

101
Q

in delta90 cycB mutants:

A

JUST READ IT

102
Q

the job of securin is to bind and inactivate a protease called ______________

A

separase

103
Q

type of protein that separase is

A

protease

104
Q

securin _______________ separase

A

inactivates

105
Q

once the APC targets the destruction box on securin, securin gets destroyed which allows _____________ to be activated

A

separase

106
Q

the target of separase is _________ component of the ________________ complex and if you break that part of the ring then it is responsible for anaphase because it allows the sister chromatids to separate and be pulled apart towards the poles

A

SCC1, cohesin

107
Q

securin has a _____________ ______ that allows it to be targeted for destruction by the APC by ubiquitination

A

destruction box

108
Q

Destruction box mutants of securin results in failed sister chromatid segregation and metaphase arrest that looks just like ________ __________________

A

APC mutants

109
Q

Destruction box mutants of securin results in failed sister chromatid segregation and _____________ arrest that looks just like APC mutants

A

metaphase

110
Q

mutants that do not produce ________________ at all segregate chromosomes prematurely and incorrectly, before anaphase

A

securin

111
Q

the main purpose of securin is to ____________ _______________

A

prevent anaphase

112
Q

2 purposes of the APC cdc20:

A

destroy cyclin, destroy securin

113
Q

APC mutants arrest in ________________

A

metaphase

114
Q

APC and securin double mutants arrest in _________ ______________ (because cyclin B not being degraded would be the thing that causes the arrest since without APC it would not be degraded but without securin at least it can leave metaphase and separate)

A

late anaphase

115
Q

securin prevents anaphase by _________________ _________

A

protecting SCC1

116
Q

in APC mutants, securin is ______________

A

stable (associated with DNA)

117
Q

in securin mutants and in securin and APC double mutants, securin is _______________

A

unstable (separase do be choppin)

118
Q

in separase mutants, SCC1 is ____________ and mitosis arrests in _______________

A

stable, metaphase

119
Q

what technique did they use to find separase association with securin?

A

co-immunoprecipitation

120
Q

securin and separase double mutants arrest in ______________ and have a ____________ SCC1

A

metaphase, stable

121
Q

the APC is not able to ubiquitinate securin or cycB until all chromosomes are properly attached to kinetochore microtubules via _____________ ________________

A

amphitelic attachment

122
Q

so what keeps the APC inactive?

A

SAC (spindle assembly checkpoint)

123
Q

experiment to find the gene that codes for spindle assembly checkpoint:

A

JUST READ IT

124
Q

colchicine and vinblastine are _______________ _______________ drugs

A

microtubule destabilizing

125
Q

taxol is a _______________ _______________ drug

A

microtubule stabilizing

126
Q

when cells are treated with colchicine, vinblastine, or taxol, CDK activity is ___________, and cyclin B and securin are ___________

A

high, stable

127
Q

__________ mutants enter anaphase prematurely, before all kinetochores have attached to spindle properly (and so the cells treated with colchicine, vinblastine, and taxol that are this type of mutant will still get to anaphase)

A

mad2 (a type of SAC)

128
Q

mad2 and APC double mutants behave like APC mutants and arrest at _______________

A

metaphase (therefore mad2 and SAC function genetically upstream of APC) (also provides evidence that SAC inhibits APC)

129
Q

since mad2 / APC double mutants arrest at metaphase like APC mutants, it can be said that mad2 or SAC functions _______________ genetically of APC

A

upstream

130
Q

a complex of proteins, called the ___________ ____________ _________________ is active at kinetochores that are not attached to spindle microtubules

A

spindle assembly checkpoint (SAC)

131
Q

at kinetochores that are not attached to spindle microtubules, the SAC component ________ is activated and diffuses away to bind to cdc20 and inhibit cdc20

A

mad2

132
Q

mad2, once activated, diffuses away and inhibits ________, preventing securin and cycB destruction

A

cdc20 (subunit of the APC)

133
Q

kinetochore spindle attachment inactivates the SAC/mad2 component and leads to _______ activation

A

APC

134
Q

model where trapezoid mad2 cycles from cytoplasm to kinetochore and back to cytoplasm and in cycling it converts from inactive form to active triangle form mad2 and then the triangle form can go bind to cdc20 and inactivate it - important thing even if it is just one chromosome that has not attached to spindle

A

kiss and run model

Molecular cell bio (8 decks)

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