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Cell Bio > Membrane Trafficking > Flashcards

Membrane Trafficking Flashcards

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Biology 101 flashcards
1
Q

what is a way for our cells to communicate with the outside world or larger body than found in the cells

A

plasma membrane

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2
Q

what do vesicles contain

A

cargo

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3
Q

exocytic (secretory) pathway

A

default pathway which is from the ER, Golgi, vesicles and outside of the cell

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4
Q

endocytic pathway

A

bringing things into the cell

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5
Q

retrieval pathway

A

Kdel signal sequence comes into play when it accidentally sends a protein out that was supposed to stay in the ER

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6
Q

Where do vesicles start

A

ER

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7
Q

vesicles must be

A

selective and targeted

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8
Q

budding off of donor compartment traps them in the

A

target compartment

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9
Q

are there markers on vesicle surfaces that determine their final destinations

A

yes

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10
Q

what do we rely on to know where things go in the cell

A

phosphotidylinositol

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11
Q

PI is

A

phosphorylated at particular ring positions by kinases unique to each organelle

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12
Q

what binds to PIPS to target vesicles

A

coat proteins

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13
Q

clathrin transport mechanism

A

endocytic

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14
Q

COPI transport mechanism

A

retrograde or retrieval

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15
Q

COPII transport mechanism

A

anterograde or exocytic or secretory

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16
Q

where does clathrin orginate

A

plasma mebrane

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17
Q

where does COPI originate

A

golgi

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18
Q

where does COPII originate

A

endoplasmic reticulum

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19
Q

clathrin coats form

A

coated pits in cytosol

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20
Q

a triskelion is composed of

A

3 heavy and 3 light polypetide chains

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21
Q

do triskelions spontaneously assemble

A

yes in a symmetrical basket structure even without the membrane

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22
Q

clathrin coats rely on a series of

A

adaptor proteins and membrane-bending proteins

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23
Q

when clathrin is released from the membrane they are transported

A

naked

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24
Q

two functions of adaptins

A
  1. bind to clathrin coat to the membrane
  2. trap transmembrane proteins that capture soluble cargo molecules inside the vesicle
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25
Q

adaptins come in and facilitate recruitment of cargo receptors to…

A

recruit clathrin

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26
Q

adaptor proteins form an…

A

inner vesicle coat

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27
Q

the bud formation is what kind of dominated process

A

clathrin

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28
Q

do you need energy for the bud formation of clathrin

A

no it forms in absence of energy

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29
Q

the basket structure by triskelion forces the flexible membrane to buldge inward called

A

invaginaiton

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30
Q

what helps pinch off the vesicle after the budding process

A

dynamin

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31
Q

is dynamin an ATPase or GTPase

A

GTPase

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32
Q

what does dynamin do

A

hydrolyzes GTP rapidly and tightens itself around the tail to form vesicle

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33
Q

what kind of binding domain does dynamin have

A

PI(4,5)P2

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34
Q

dynamin wraps so tightly forcing the two inside leaflets of the vesicle membrane to

A

fuse

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35
Q

once dynamin does its job

A

we strip the coat

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36
Q

what recruits dynamin

A

PIPS

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37
Q

if there are no PIPS we loss

A

affinity for clathrin and dynamin

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38
Q

how do we strip the coat of clathrin

A

we have chaperone proteins that will act as ATPases

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39
Q

what chaperone protein strips the clathrin coat

A

HSP70

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40
Q

PIP phosphatases inside the vesicle which depletes PI(4,5)P2 from membrane weakening

A

the adaptor proteins

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41
Q

COPII requires what pathway

A

exocytic pathway

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42
Q

COPII vesicle assembly requires a

A

Sar1 Coat-recruitment GTPase

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43
Q

inactive Sar1-GDP is converted to what and by what

A

Sar1-GTP by Sar1-GEF

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44
Q

the inactivation of Sar1-GDP exposes an

A

amphiphilic helix which embeds Sar1 in the ER membrane

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45
Q

Sar1-GEF is only found in the

A

er membrane

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46
Q

how does Sar1 know to go to the er membrane

A

it is the only place where it gets turned on

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47
Q

when a vesicle needs to bud off the er the Sar1-GDP will come down and associate with

A

Sar-GEF

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48
Q

Sar-GEF kicks off GDP and allows

A

GTP to bind

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49
Q

Sar1-GTP changes the shape and tail which makes the tail

A

pop out and be exposed to the cytosolic side of the er membrane

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50
Q

Sar1-GTP recruits

A

adaptor proteins

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51
Q

Sar1-GTP binds to adaptor proteins which are

A

Sec 23 and Sec24

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52
Q

Sec24 binds to

A

cargo receptors

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53
Q

Sec23/24 start to

A

invaginate the membrane

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54
Q

Adaptor proteins in COPII recruit

A

outer coat proteins

55
Q

what proteins in COPII form the outer coat and pinches off the vesicle?

A

Sec13/31

56
Q

COPII uncoating we hydrolyze Sar-GTP to

A

Sar-GDP

57
Q

once GTP in COPII is hydrolyzed the coat disassembles and Sar1-GDP returns to

A

its inactive, cytosolic form

58
Q

are vesicles always round in COPII

A

no

59
Q

what pathway does COPI require

A

retrieval pathway

60
Q

COPI is the same as COPII but with different

A

GTPases and coat proteins

61
Q

COPI vesicles require what GTPase

A

Arf1-GDP and Arf1-GTP

62
Q

What GTPases are exposed on the surfaces of membranes

A

Rab Proteins

63
Q

there are more than how many rab proteins

A

60

64
Q

rab effectors act as …

A

tethers to catch the vesicle

65
Q

can the rab split around the cytoplasm

A

yes

66
Q

inactive rabs (rab-GDP) are found in the

A

cytosol

67
Q

do Rab-GEFs activate rabs (to rab-GTP) on both vesicles and target membrane

A

yes

68
Q

active rab-GTP binds to

A

membranes

69
Q

effectors include

A

motor proteins and tethering proteins

70
Q

motor proteins move

A

vesicles along cytoplasm

71
Q

tethering proteins link

A

two membranes together

72
Q

what do we kick off when rab proteins guide the vesicles

A

GDI

73
Q

GDI is

A

GDP dissociation inhibtor

74
Q

what mediates membrane fusion

A

snares

75
Q

what do snares do

A

fuse the membranes together

76
Q

snares exist in

A

complement

77
Q

v-SNARE is on

A

the vesicle

78
Q

t-SNARE is on

A

the target membrane

79
Q

what side are snares on

A

cytosolic side

80
Q

how do snares cause membrane fusion

A

the t-snare and v-snare wrap around so tightly causing fusion

81
Q

SNAREs form 4-helix bundles that

A

exclude water

82
Q

does the water layer between membranes prevent fusion

A

yes that is why we need snares

83
Q

disassembly of snares require

A

energy

84
Q

the helical bundles of snares are

A

energetically favorable

85
Q

pulling snares apart require the action of

A

NSF

86
Q

NSF is an

A

ATPase

87
Q

COPII vesiciles exit the er on

A

smooth er

88
Q

soluble proteins need an exit ticket to the er and must be

A

folded properly

89
Q

as we send vesicles out you to the golgi you …

A

strip the coat off

90
Q

everything that needs to be moved in a cell has to be moved along ? and transported through by

A

microtubules
motor proteins

91
Q

ER vesicles come together to form larger

A

VTCs or vesicular tubular clusters

92
Q

VTCs bud off on their own transport vesicles and return escaped proteins and proteins needed only for? and is called

A

budding
retrieval transport

93
Q

ER proteins are retrieved in COPI vesicles via

A

KDEL signal sequences

94
Q

KDEl receptors are sent back to ER in

A

COPI vesicles derived from VTC

95
Q

KDEL is what type of terminal amino acid sequence

A

C-terminal

96
Q

Where do KDEL receptors orginate

A

ER

97
Q

what prevents KDEL receptors from binding in the wrong place?

A

pH

98
Q

ER to golgi does what to pH

A

decreases it

99
Q

what is the sorting center of the cell?

A

golgi

100
Q

cis side is closest to the…

A

ER

101
Q

trans cisterna is …

A

outside of the cell

102
Q

true or false: there are a series of protein modification enzymes in each cisterna

A

true

103
Q

traffic is what direction within the golgi?

A

one-way, though some vesicles are sent back to the ER

104
Q

are things completely changed throughout the golgi process

A

yes

105
Q

internal membrane proteins are highly glycosylated to protect them from

A

proteases

106
Q

hydrolases work in a basic or acidic environment

A

acidic

107
Q

the lysosome is a cellular stomach because it

A

routes things that are in vesicles to be degraded and destroyed or recycled

108
Q

autophagy

A

cellular structures are no longer functional or needed

109
Q

receptor-mediated endocytosis

A

endosomes from cell membrane containing molecules that must be processed. these can fuse with lysosomes

110
Q

phagocytosis

A

large particles and microorganisms from the outside

111
Q

pinocytosis

A

cellular drinking/ pulling in extracellular fluid

112
Q

3 sources of digestive material can fuse with lysosomes

A

autophagy, endocytosis, phagocytosis

113
Q

where does autophagy originate

A

cytoplasm of the cell

114
Q

receptor-mediated endocytosis is what kind of mediated process

A

clathrin

115
Q

receptors in endocytosis are embedded where

A

plasma membrane

116
Q

receptors embedded in the plasma membrane bind to

A

extracellular cargo and bring it into the cell

117
Q

receptors are recycled through

A

exocytosis back to PM

118
Q

cargo is sent to the

A

golgi for sorting or lysosome for destruction

119
Q

is cholesterol bad

A

no

120
Q

HDL

A

high density lipoprotein

121
Q

can cholesterol dissolve in blood

A

no its hydrophobic

122
Q

how is cholesterol transported through the bloodstream

A

through carriers called lipoproteins

123
Q

LDL

A

low density lipoprotein

124
Q

Is HDL bad or good

A

good

125
Q

is LDL bad or good

A

bad

126
Q

most cholesterol hormones exist in what form

A

LDL form

127
Q

hydrolytic enzymes in the lysosome convert the cholesterol esters to

A

free cholesterol

128
Q

two examples that exhibit phagocytic cells

A

macrophages and neutrophils

129
Q

exocytosis consists of 2 pathways

A

constitutive secretion (common)
regulated secretion

130
Q

in constitutive secretion if the secretory vesicle is not tagged,…

A

it will leave the trans golgi and fuse with the cell membrane

131
Q

in regulated secretion, the secretory vesicles store the molecule until

A

some signal stimulates their fusion with the cell membrane and release of contents

132
Q

in regulated secretion the secretory vessels wait near the…

A

plasma membrane until signaled to release their contents

133
Q

histamine secretion is in what cells

A

mast

134
Q

what emplys an intricate system of targetted exocytosis and endocytosis to send/receive appropriate signals

A

neurons

Cell Bio (5 decks)

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