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Cell Biology > Exam 3 > Flashcards

Exam 3 Flashcards

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1
Q

What molecules do vesicles carry between compartments?

A

soluble proteins and membrane proteins

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2
Q

What is vesicle budding driven by?

A

assembly of a protein coat

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3
Q

What does vesicle docking depend on?

A

Tethers and SNAREs

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4
Q

Where do transport vesicles carry proteins?

A

Golgi apparatus

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5
Q

What part of the cell is responsible for lipid production?

A

smooth ER

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6
Q

True or false, lipid proteins are transported by transport vesicles to the Golgi.

A

true

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7
Q

What secretes from the Golgi?

A

hormones

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8
Q

Can the endomembrane system be modified?

A

yes, depending on the cell type

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9
Q

Transport occurs between compartments in what?

A

endomembrane system and the plasma membrane

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10
Q

Endocytotic mechanisms are destined for what?

A

lysosomes

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11
Q

What protein coats vesicles?

A

Clathrin

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12
Q

What shape do clathrin molecules assemble into?

A

basket like cages

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13
Q

What do clathrin molecules do?

A

help shape membranes into vesicles

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14
Q

Formation of baskets on the membrane leads to what?

A

reformation and internalization

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15
Q

Where does clathrin form baskets?

A

endocytotic site

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16
Q

Why do vesicles form?

A

to internalize things outside of the cell

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17
Q

What pinches the vesicle from the membrane?

A

Dynamin (GTPase)

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18
Q

What does clathrin bind to?

A

adaptin

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19
Q

The binding of clathrin and adoption do what?

A

buds the vesicle until its pinched off by Dynamin

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20
Q

The vesicle distorts, doing what?

A

allows clathrin and adaptin to fall off leaving carboxy terminal domains of receptors

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21
Q

Where is the initial site of adaptin assembly?

A

carboxy terminal domains of the receptors

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22
Q

What are Tethers and SNAREs?

A

proteins

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23
Q

What does vesicle docking involve?

A

membrane proteins, v-snares, and t-snares

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24
Q

Where are V-SNARES?

A

on vesicles

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25
Q

here are T-SNAREs?

A

on target membrane

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26
Q

What does the RAB protein bind to?

A

vesicles containing cargo

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27
Q

What initiates membrane fusion?

A

t-snare binding to v-snare

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28
Q

What releases vesicle cargo to next compartment?

A

membrane fusion

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29
Q

RAB binding to a tethering protein pulls what?

A

v-snares and t-snares

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30
Q

Where are most proteins modified?

A

in the ER

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31
Q

What controls the size of the ER?

A

demand for protein folding

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32
Q

Where are proteins further modified and sorted?

A

Golgi

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33
Q

Secretory proteins are released from the cell by what process?

A

exocytosis

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34
Q

What event happens before proteins are sent to the Golgi?

A

glycosylation event

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35
Q

What amino acid are many proteins glycosylated on in the ER?

A

asparagine

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36
Q

What membrane lipid delivers Oligosaccharide to a protein?

A

Dolichol

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37
Q

What catalyzes the transfer of oligosaccharides from Dolichol to Asparagine?

A

the enzyme oligosaccharyl transferase

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38
Q

Where do ER proteins enter the Golgi?

A

the cis face

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39
Q

Proteins are glycosylated as they travel through what?

A

Golgi Cisternae

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40
Q

Where do proteins exit the Golgi?

A

trans face

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41
Q

The Golgi consists of what?

A

stack of flattened membrane enclosed sacs

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42
Q

What part of the Golgi does most glycosylation happen?

A

medial cisterna

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43
Q

What element triggers the release of secretory proteins?

A

Calcium

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44
Q

What are the 2 pathways of exocytosis?

A

regulated and constitutive

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45
Q

Where do the regulated and constitutive pathways diverge?

A

trans Golgi network

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46
Q

Is the constitutive pathway regulated?

A

no

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47
Q

What do secretory vesicles do?

A

store and release concentrated proteins

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48
Q

What do specialized phagocytic cells ingest?

A

large particles

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49
Q

Pinocytosis takes up what?

A

fluid and macromolecules

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50
Q

Receptor-mediated endocytosis provides what into animal cells?

A

specific route

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51
Q

Where are endocytose macromolecules sorted?

A

endosomes

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52
Q

Lysosomes are the principle site of what?

A

intracellular digestion

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53
Q

Is pinocytosis constantly happening?

A

yes

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54
Q

Is phagocytosis a triggered process?

A

yes

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55
Q

Is receptor mediated cytosine triggered?

A

yes

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56
Q

What does phagocytosis do?

A

completely changes the cell membrane and completely envelopes an invader

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57
Q

What do pseudopods do?

A

wrap and surround the particle to be digested

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58
Q

In what process does the cell membrane fold and create small pockets and captures the cellular fluid and dissolved substances?

A

pinocytosis

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59
Q

What are some examples of pinocytosis?

A

microvilli of the small intestines and ducts of the kidneys

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60
Q

What is a example of receptor mediated endocytosis?

A

cholesterol internalization from the blood stream

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61
Q

Where does LDL enter the cells?

A

via receptor-mediated endocytosis

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62
Q

Where can viruses enter cells?

A

receptor0mediated cytosis

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63
Q

Lysosomes contain a variety of what that are only active under acidic conditions?

A

hydrolytic enzymes

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64
Q

Do lysosomes originate from the Golgi?

A

no

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65
Q

Lysosomes are the result of what?

A

endocytic chamber forming

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66
Q

What pathways do materials destined for degradation follow?

A

endocytosis, phagocytosis, and autophagy (auto phagocytosis)

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67
Q

Delivery of vesicle to the lysosomes comes from where?

A

the Golgi

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68
Q

Can cell signals act over a long or short range?

A

yes

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69
Q

What do all responses depend on?

A

a signal from the cell

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70
Q

What do receptors trigger in a cell?

A

molecular switches

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71
Q

What are the purpose of cell-surface receptors?

A

relay extracellular signals via intracellular signaling pathways

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72
Q

What molecules act as molecular switches?

A

some intracellular signaling proteins

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73
Q

What do ion-channel-coupled receptors convert?

A

chemical signals into electrical signals

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74
Q

What is signal transduction?

A

process where one type of signal is converted into another. example chemical into electrical

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75
Q

What are the 2 mechanisms of extracellular signaling molecules?

A

bind to cell-surface receptors or bind to intracellular receptors (hydrophobic)

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76
Q

What is Acetylcholine an example of?

A

a signaling molecule that can induce different responses in different target cells

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77
Q

What cellular signals have multiple different functions?

A

cell survival, division of cell, different structures and functions of cells, cell death trigger

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78
Q

How do fast extracellular signals act?

A

through existing protein function

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79
Q

How do slow extracellular signals act?

A

through changes in transcription or protein synthesis

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80
Q

Describe cell-surface receptors.

A

on plasma membrane (are membrane proteins)
synthesized on the rough ER
enter vesicle transport to Golgi
goes through glycolysis
alpha helical shape

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81
Q

Signaling molecules eventually interact with what kind of protein?

A

specific effector proteins

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82
Q

What do altered effector proteins do?

A

change the behavior of the cell

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83
Q

Signaling molecules can effect final response elements (proteins), this has what sort of effect?

A

metabolism, shape, genes expression

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84
Q

What is Protein Phosphorylation and GTP binding proteins an example of?

A

intracellular signaling proteins that can act as molecular switches

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85
Q

Explain protein phosphorylation.

A

transfers phosphates to initial target, signal is now being transducted. keeps target dephosphorylated

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86
Q

Explain GTP proteins.

A

when they are in a state v fund to GTP they are off, hydrolysis of GTP turns the signal on (these are 2 different pathways)

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87
Q

What are the 3 main classes of cell-surface receptors?

A

ion-channel coupled
G protein coupled
enzyme coupled

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88
Q

What is a GCPR?

A

Guanine Protein Coupled Receptor

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89
Q

What does stimulation of GCPR’s do?

A

activates G protein subunits

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90
Q

What can the Cyclic AMP Signaling Pathway do?

A

activate enzymes and turn on genes

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91
Q

What does the Inositol Phospholipid Pathway trigger?

A

rise in intracellular Ca2+

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92
Q

In a GCPR signaling pathway what dissolved gas is generated to carry a signal to the adjacent cells?

A

NO (nitrous oxide)

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93
Q

Activation of G protein subunits is also known as what?

A

G protein coupled signaling

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94
Q

How does GCPR activate G proteins?

A

by inducing the exchange of GDP for GTP at the alpha subunit

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95
Q

The G protein alpha subunit is switched of by…

A

hydrolyzing its bound GTP to GDP

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96
Q

Do some G proteins directly regulate ion channels?

A

yes

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97
Q

What enzyme is Cyclic AMP synthesized by?

A

Adenylyl Cyclase

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98
Q

What enzyme degrades Cyclic AMP?

A

Cyclic AMP phosphodiesterase

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99
Q

True or False. Nucleotides can be coenzymes or signaling molecules.

A

true

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100
Q

Do Cyclic AMP level rise or lower rapidly in response to an extracellular signal?

A

rise

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101
Q

A rise in intracellular cyclic AMP can activate what?

A

gene transcription

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102
Q

Epinephrine stimulates the breakdown of what in skeletal muscles?

A

glycogen

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103
Q

What triggers the release of Ca2+ from internal storage sites into the cytosol?

A

inositol phospholipid pathway

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104
Q

Elevtaed cytosolic Ca2+ can activate what?

A

calmodulin dependent pathways

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105
Q

Calmodulin dependent pathways activate via what?

A

calmodulin dependent kinase (CAM-kinase)

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106
Q

Fertilization of an egg leads to what happening?

A

results in a wave of calcium along the whole cell

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107
Q

Where is a major calcium storage site?

A

in the cellular ER

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108
Q

The inositol phospholipid signaling pathway is what kind of signaling cascade?

A

heterogemeric

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109
Q

What is the result of IP3 being triggered by the GPCR system?

A

calcium will constantly be dumping out of the ER

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110
Q

What are the first 2 steps in the Inositol Phospholipid pathway?

A
  1. ligand binds to GPCR activating G-proteins and activating Phospholipase C
  2. Phospholipase C activates 2 signaling pathways
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111
Q

What are steps 3 & 4 of the Inositol Phospholipid pathway?

A
  1. Phospholipase C dissociates IP3 and Diacyl Glycerol from a membrane bound Inositol phospholipid
  2. IP3 binds to Ca2+ channels on the ER, this triggers Ca2+ release from the ER
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112
Q

What are steps 5 & 6 of the Inositol Phospholipid pathways?

A
  1. elevated cytosolic Ca2+ and released diacyglycerol work together to activate Protein Kinase C (PKC)
  2. PKC phosphorylates numerous protein targets to generate cell response
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113
Q

What is phospholipase?

A

hydrolyzed phospholipids

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114
Q

What changes the shape of the calmodulin protein?

A

calcium binding

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115
Q

How many calciums bind to calmodulin?

A

4

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116
Q

What is chemotaxis?

A

movement of cell or molecule with the concentration gradient

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117
Q

The activation of RTK stimulates what?

A

the assembly of an intracellular signaling complex

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118
Q

Active phosphorylated RTKs provide what for other signaling proteins?

A

docking sites

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119
Q

What are inactive RTKs?

A

membrane proteins

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120
Q

What are some examples of signals in a cell?

A

local, cell cell, ion, long range diffusible, and neurotransmitters

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121
Q

What controls nerve cell production in the fruit fly Drosophila?

A

notch signaling

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122
Q

What is the signal protein in a Drosophila called? receptor protein?

A

delta; notch

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123
Q

Are delta and notch proteins transmembrane?

A

yes

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124
Q

What results in the binding of delta to notch?

A

proteolysis of the receptor

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125
Q

When delta notch complex is cut off it floats, then what happens?

A

the GDP system transports it to the nucleus

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126
Q

Does notch serve in binding and transcription factors?

A

yes

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127
Q

Explain steroid signaling.

A

small hydrophobic hormones bind to intracellular receptor that act as transcription regulators

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128
Q

What do all steroid hormones have?

A

cholesterol backbone

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129
Q

Are steroid hormones amphipathic?

A

yes

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130
Q

What does amphipathic mean?

A

they can just pass through

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131
Q

Explain the steroid hormone cortisol.

A

acts by activating a transcription regulator in cytosol
cortisol receptor protein complex moves to the nucleus
it controls gene transcription

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132
Q

Explain signaling integration “crosstalk”.

A

intracellular signaling proteins serve to integrate multiple external incoming signals

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133
Q

What are the 3 filaments in the cytoskeleton?

A

intermediate filaments
actin
microtubules

134
Q

Describe there cytoskeleton.

A

gives a cell shape
allows cell to organize internal compartments
allows generation of force for movements

135
Q

What is the Golgi structured around?

A

microtubules

136
Q

Explain intermediate filaments.

A

very fibrous, like ropes
form net/meshwork throughout cell
associate with cell cell contact points
has high tensile strength

137
Q

How big are intermediate filaments?

A

10 nm

138
Q

Explain microtubules.

A

not solid
helical distribution
more rigid than actin
more dynamic than filament proteins
not very strong

139
Q

How big are microtubules?

A

25 nm

140
Q

What is actin also known as?

A

microfilaments

141
Q

What is actin the main component of?

A

muscle

142
Q

Explain actin.

A

helical polymer
undergoes dynamic assembly and disassembly constantly
concentrated around cell periphrie
fingerlike extensions

143
Q

How big are actin?

A

7 nm

144
Q

Are intermediate filaments found in plants and lower vertebrate animals?

A

no

145
Q

Are intermediate filaments, microtubules, and actin all tissue specific?

A

no, only intermediate filaments

146
Q

What is the nuclear lamina?

A

meshwork of intermediate filaments that support the nuclear envelope

147
Q

Explain how intermediate filaments are formed.

A

8 thinner strands twisted into a rope
dimers then arranged in opposite orientations
tetramers link end to end
8 tetramers twist into the rope like filament

148
Q

What are intermediate filaments associated with?

A

desmosomes

149
Q

Are intermediate filaments good for transport?

A

no, they do not have direction

150
Q

Is there energy required to form an intermediate filament?

A

no energy is required

151
Q

What are the 2 types of intermediate filaments?

A

cytoplasmic and nuclear

152
Q

What are the subclasses of cytoplasmic filaments?

A

keratin filaments- epithelial cells
vimentin and vimentin related- connective tissue cells. muscle cells, and glial cells
neurofilaments- nerve cells

153
Q

What is the subclass of nuclear filaments?

A

nuclear lamins- in all animal cells

154
Q

What makes skin more prone to blistering?

A

mutant form of keratin

155
Q

What are lamins?

A

intermediate filaments that support snd strengthen the nuclear envelope
form network at base of nuclear envelope
provide attachment site for chromosomes

156
Q

What is progeria?

A

premature aging

157
Q

What causes progeria?

A

mutations in lamin A

158
Q

Describe plectin.

A

protein that aids in bundling of intermerdiate filaments

159
Q

What is plectins function?

A

links intermediate filaments to other cytoskeleton components such as actin and microtubules

160
Q

What are KASH proteins?

A

on cytoplasmic membrane on outer nuclear envelope

161
Q

What are SUN proteins?

A

anchored on the inner nuclear envelope

162
Q

Does plectin affect KASH and SUN if disrupted?

A

yes

163
Q

What is the function of KASH?

A

binds microtubules, motors, plectins, or actin

164
Q

What is the function of SUN?

A

bind chromatin or nuclear lamina

165
Q

Wha6tis the major microtubule organizing center?

A

the centrosome

166
Q

Where do microtubules originate from?

A

the centrosome

167
Q

What happens if microtubules are depolymerized?

A

the Golgi disorganizes

168
Q

What are cilia and flagella important for?

A

cell motility

169
Q

Are centrosomes organizing centers?

A

yes

170
Q

How many centrosomes do cells normally have?

A

one

171
Q

Do plants have centrosomes?

A

no, most of them do not

172
Q

Are microtubules hollow tubes?

A

yes

173
Q

What are microtubules made out of?

A

globular tubular subunits (alpha beta dimers)

174
Q

How many subunits are in a microtubule cross section?

A

13 subunits

175
Q

How many GTP binding sites do microtubules have?

A

two

176
Q

What do protofilaments do for microtubules?

A

give them their helical structure

177
Q

Is the beta tubular end positive or negative?

A

positive

178
Q

Is the alpha tubular end positive or negative?

A

negative

179
Q

Where does tubular polymerize on a centrosome?

A

nucleation sites

180
Q

Describe y-Tubulin.

A

embedded in pericentriolar centrosome matrix as “ring complexes”

181
Q

Where does nucleation take place?

A

negative end of the tubule

182
Q

Describe microtubule dynamic insability.

A

not permanent when it polymerizes

183
Q

Does each microtubule grow and shrink independently of its neighbor?

A

yes

184
Q

How are microtubules stabilized?

A

capping proteins that bind to the ends of the positive ends

185
Q

What happens during polymerization of microtubules?

A

alpha beta dimers GTP adds to positive end forming a GTP cap

186
Q

Loss of the GTP cap results in what?

A

microtubule polymerization

187
Q

What does the Kinesin motor do?

A

hydrolyzes ATP and moves toward MT plus end

188
Q

at does the Dynein motor do?

A

hydrolyzes ATP and moves toward MT minus end

189
Q

What drives intracellular transport?

A

motor proteins

190
Q

How do motor proteins move along microtubules?

A

using their globular heads

191
Q

Where are ATPase domains?

A

glubular heads

192
Q

What is the lagging foot and can lift?

A

ATP

193
Q

What is the front foot and is bound?

A

ADP

194
Q

What do adaptors signal for?

A

binding of kinesins or dyneins

195
Q

How are microtubules in a cilium or flagellum arranged?

A

“9 + 2” array (9 doublet microtubules, 2 center microtubules)

196
Q

What does the movement of Dynein cause?

A

cilia and flagellum to bend

197
Q

Describe actin filaments.

A

thin and flexible

198
Q

Do actin and tubular polymerize by different mechanisms or the same?

A

similar mechanisms

199
Q

What underlies the plasma membrane in most eukaryotic cells?

A

a cortex rich in actin filaments

200
Q

What can alter the arrangement of actin filaments?

A

extracellular signals

201
Q

What influences the type of protrusions formed at the leading edge?

A

actin binding proteins

202
Q

What allows animal cells to adopt a variety of shapes to perform a variety of functions?

A

actin filaments

203
Q

What do actin monomers polymerize into?

A

filaments

204
Q

Do actin filaments have polarity?

A

yes, they have a + end and - end

205
Q

What does actin polymerization require?

A

ATP, actin ATP monomer adds to plus end of polymer

206
Q

What can actin filaments undergo?

A

tread milling

207
Q

What controls the behavior of actin filaments?

A

actin binding proteins

208
Q

How does actin help the cells move forward?

A

forces generated in the actin filament rich cortex

209
Q

What pushes the leading edge of the lamellipodium forward?

A

web of polymerizing actin filaments

210
Q

How is the plus end of newly polymerized actin stabilized?

A

capping protein

211
Q

What does the stabilization of a polymerized actin filament result in?

A

branching structures that push the plasma membrane forward

212
Q

What does actin associate with to form contractile structures?

A

myosin

213
Q

What is involved in organelle movement?

A

myosin 1

214
Q

What is involved in muscle contraction?

A

myosin 2

215
Q

Does myosin 1 contain a tail region?

A

no

216
Q

Does myosin 2 contain a tail region? if so what does it form?

A

yes myosin 2 filaments

217
Q

What are the 4 phases of the eukaryotic cell cycle?

A

G1, S, G2, M

218
Q

What triggers the major processes of the cell cycle?

A

a cell cycle control system

219
Q

What happens in the M phase?

A

division

220
Q

What happens in the G1 phase?

A

longest phase, is the growth phase

221
Q

What happens in the S phase?

A

DNA synthesis

222
Q

What happens in the G2 phase?

A

gap phase between S and M

223
Q

What do checkpoints do in the cell cycle?

A

won’t allow the next phase to start until specific things are checked off

224
Q

What do checkpoints in the cell cycle measure?

A

tension

225
Q

What does the cell cycle control system (checkpoints) depend on?

A

cyclically activate protein kinases called CDKs (cyclin dependent kinases)

226
Q

How are cyclin concentrations regulated?

A

transcription and proteolysis

227
Q

What does the activity of cyclin-CDK depend on?

A

phosphorylation and dephosphorylation

228
Q

What can block CDK activity?

A

CDK inhibitor proteins

229
Q

How can the protein cyclin be controlled?

A

by synthesis, disruption, or post translational modification

230
Q

How was MPF discovered?

A

discovered by injecting fertilized Xenopus egg cytoplasm into Xenopus oocytes

231
Q

What does progression through the cell cycle depend on?

A

CDKs

232
Q

Kinase is only active when what is present?

A

cyclin

233
Q

Cyclin responds to what sort of activity?

A

MPF

234
Q

Cyclins are destroyed as mitosis stops, this corresponds with what?

A

metaphase anaphase transition

235
Q

What does S-cyclin do?

A

initiates DNA replication cycle and hangs on until M phase

236
Q

What is the regulator in the cell cycle control system?

A

timed destruction

237
Q

What is cyclin degradation through?

A

ubiquitin dependent proteasome

238
Q

What is the signal for the destruction of cyclin?

A

ubiquitylation

239
Q

What is ubiquitin?

A

small protein

240
Q

Polyubiquitin forms on proteins targeted for what?

A

destruction

241
Q

What enzyme gives polyubiquitin?

A

E3 ligase

242
Q

What does APC (E3 ligase complex) do?

A

targets cyclin, initiates destruction, and promotes metaphase to anaphase transition

243
Q

Can CTK kinase work without cyclin?

A

no

244
Q

What post translational modification can prevent CTK from working?

A

phosphorylation

245
Q

What is the response element to DNA damage?

A

P27

246
Q

What can control the CTK?

A

protein binding

247
Q

What is Mitosis?

A

nuclear division

248
Q

What is Cytokinesis?

A

cytoplasmic divison

249
Q

What are the 4 phases of Mitosis?

A

prophase
metaphase
anaphase
telophase

250
Q

What is the result yielded from Cytokinesis?

A

2 identical daughter cells

251
Q

Describe a cell cycle checkpoint.

A

ensures that key processes in the cycle occur in the proper sequence

252
Q

What drives the cell cycle?

A

synthesis and degradation of cyclin proteins

253
Q

Does DNA need to be replicated multiple times or only once?

A

only once

254
Q

What is stably inactivated in G1?

A

CDKs

255
Q

Mitogens promote what that stimulates cell division?

A

the production of cyclins

256
Q

What is something that can temporarily halt the progression through G1?

A

DNA damage

257
Q

How can cells delay division for prolonged periods?

A

by entering specialized nondividing states

258
Q

What is one way to stimulate cell proliferation?

A

inhibiting the Rb protein (retinoblastoma)

259
Q

What is the Rb protein?

A

tumor suppressor that inhibits cell cycle progression

260
Q

How does the Rb protein inhibit progression in the cell cycle?

A

binds to transcription factors that promote cell replication

261
Q

What enzyme is constantly surveying to make sure that DNA is continuous?

A

ligase

262
Q

What is the “guardian of the genome”?

A

P53

263
Q

What happens to P53 is DNA damage isnt present?

A

it gets degraded in the proteasome

264
Q

What does P2bind to in order to block it from working?

A

cyclin CDK complex

265
Q

What activates and stabilizes P53?

A

DNA damage

266
Q

What stimulates the transcription of P21?

A

activation and accumulation of P53

267
Q

What does P21 inhibit?

A

G1/S phases and S-CDKs

268
Q

What happens if P53 is mutated?

A

damaged DNA will be replicated through mitosis

269
Q

DNA damage activates what that phosphorylates P53?

A

kinases

270
Q

Is phosphorylated P53 degraded by proteolysis?

A

no

271
Q

What does S-CDK do?

A

initiates DNA replication and blocks re-replication

272
Q

What can incomplete replication do to the cell cycle in G2?

A

arrest it

273
Q

What are the 4 steps in the G1 phase of mitosis?

A
  1. ORC (origin of replication complex) is loaded onto DNA
  2. CDC6 binds to the ORC
  3. Helicase displaces ORC to form a pre replication complex
  4. ORC is loaded
274
Q

What are the 4 steps in the replication part of S phase?

A
  1. ORC is activated to initiate DNA replication
  2. S-CDK kinase phosphorylates & activates helicase
  3. S-CDK kinase phosphorylates & guides assembly of DNA polymerase & other proteins at replication fork
  4. DNA replication machinery is activated
275
Q

What are the 4 steps in S phase where DNA re-replication is blocked?

A
  1. S-CDK phosphorylates CDK
  2. CDC6 phosphorylation blocks reloading of helicase & assembly of ORC pre-replication complex
  3. helicase isn’t recruited, replication machinery is not assembled
  4. re-replication is prevented
276
Q

What is a signal for the ORC site?

A

CDC6

277
Q

What is destroyed at the metaphase anaphase transition?

A

S cyclin

278
Q

What drives the entry into mitosis?

A

M-CDK

279
Q

What helps configure duplicated chromosomes for separation?

A

cohesins and condensins

280
Q

How do you convert DNA histone complexes into supercoiled structures?

A

through interactions of cohesins and condensins

281
Q

M-cyclin activates what?

A

M-CDK

282
Q

What inhibits M-CDK?

A

phosphorylation

283
Q

M-CDK phosphorylates what?

A

CDC25 phosphatase

284
Q

How does M-CDK create a positive feedback loop?

A

activated M-CDK indirectly activates more M-CDK

285
Q

Cohesins for m rings that do what?

A

tie together 2 adjacent sister chromatids by forming until the rings are broken in late mitosis

286
Q

What do condensins do in terms of chromosome formation?

A

coil each sister chromatids into compact structures

287
Q

Does the nuclear envelope have to breakdown in M phase?

A

yes

288
Q

What proteins are responsible for the structure of the nuclear envelope?

A

lamin proteins

289
Q

What happens in lamin is phosphorylated?

A

the nuclear envelope falls apart

290
Q

How many transient cytoskeletal structures mediate M phase in animal cells?

A

2

291
Q

What helps form the 2 poles of the mitotic spindle?

A

G2/M transition centrosomes duplicated during S/G2

292
Q

What happens in prophase?

A

the mitotic spindle starts to assemble

293
Q

What attaches to the mitotic spindle?

A

pro metaphase chromosomes

294
Q

How do chromosomes assist in the assembly of the mitotic spindle?

A

via kinetochores

295
Q

What occurs in metaphase?

A

chromosomes line up at the spindle equator

296
Q

What happens in anaphase?

A

proteolysis triggers sister chromatid separation

297
Q

What happens in anaphase A?

A

chromosomes segregate and moves to poles

298
Q

What happens in anaphase B?

A

spindles elongate to further separate poles

299
Q

What spindle checkpoint prevent sister chromatid seperation and stop the metaphase anaphase transition?

A

unattached chromosome

300
Q

When does the nuclear envelope disassemble?

A

G2/M phase transition (lamins are phosphorylated)

301
Q

When does the nuclear envelope reform?

A

telophase (lamins are dephosphorylated)

302
Q

What is the key to the spindle assembly checkpoint?

A

kinetochores

303
Q

What keeps the lamin phosphorylated?

A

CDK

304
Q

Do kinetochores stay attached in anaphase A?

A

yes

305
Q

How is force generated in anaphase B?

A

sliding overlapping microtubules that increase the pole to pole seperation

306
Q

What helps form the 2 poles of the mitotic spindle?

A

duplicated chromosomes

307
Q

When does the mitotic spindle start to assemble?

A

in prophase

308
Q

When do chromosomes attach to the mitotic spindle?

A

prometaphase

309
Q

Do chromosomes assist in the assembly of the mitotic spindle?

A

yes

310
Q

When does centrosome duplication occur?

A

during interphase

311
Q

How do chromosomes assist in the assembly of the mitotic spindle?

A

through kinetochore microtubule interactions

312
Q

Where do kinetochores assemble?

A

chromosome centromere region

313
Q

Do kinetochores attach to the plus or minus end of the microtubule?

A

plus

314
Q

Do kinetochores contain proteins that send cell cycle stop signals in the absence of microtubule attachmetns?

A

yes

315
Q

Why are chromosome centromere regions very planar?

A

they are ATP rich

316
Q

What are the 3 classes of microtubules that make up the mitotic spindle?

A

astral, kinetochore, and interpolar microtubules

317
Q

How are interpolar microtubules stabilized?

A

by motors and microtubule associated proteins

318
Q

What do Dynein motor proteins deplete?

A

kinetochores of stop signal proteins, when a checkpoint is released

319
Q

What is APC (anaphase promoting complex)?

A

ubiquitin proteasome

320
Q

What does APC trigger?

A

cyclin degradation & loss of CDK activity

321
Q

What triggers sister chromatid seperation at anaphase?

A

proteolysis of cohesins

322
Q

What are sister chromatids held together by?

A

cohesin proteins

323
Q

What promotes the destruction of cohesin proteins?

A

APC

324
Q

Can the spindle assembly checkpoint be regulated by only one kinetochore?

A

yes

325
Q

What determines the plane of cytoplasmic cleavage?

A

the position of the mitotic spindle

326
Q

What is the contractile ring of animal cells made of?

A

actin and myosin

327
Q

Cytokinesis in plant cells involves the formation of what?

A

a new cell wall- phragmoplast

328
Q

Astral overlap creates opportunity for what to form?

A

cleavage furrow

329
Q

What shrinks the cleavage furrow?

A

actomyosin contraction

330
Q

What forms a new cell wall in plant cells?

A

vesicle fusion at equator

331
Q

What is cytokinesis in plants guided by?

A

phragmoplast

Cell Biology (4 decks)

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