Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Cell Biology > Chapter 12: Protein Sorting & Transport > Flashcards

Chapter 12: Protein Sorting & Transport Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

what are the components of the secretory pathway?

A

-RER
-SER
-Golgi
-lysosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is the function of the RER

A

protein:
- folding
- modification
- processing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is the function of the smooth ER

A

membrane & lipid synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is the function of the golgi

A

protein processing and sorting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

the secretory pathway is connected by

A

vesicular transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what experiments defines the secretory pathway?

A

labeling new proteins w/ radioactive amino acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

proteins synthesized from free ribosomes in the cytosol can be transported to

posttranslational import

A
  • nucleus
  • mitochondria
  • chloroplasts
  • peroxisomes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

proteins synthesized from membrane-bound ribosomes can be transported to

cotranslational import

A
  • Golgi
  • endosomes
  • plasma mem.
  • lysosomes
  • peroxisome membrane
  • secretory vesicles
  • nuclear mem.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

protein sorting begins during

A

translation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

which types of proteins retain their signal sequence?

A

cytosolic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

proteins translated into _________ have their signal sequence cleaved

A

microsomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

signal sequences are removed by

A

proteolytic cleavage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what are the 2 mechanisms for targeting proteins to the ER

A
  • cotranslational translocation
  • posttranslational translocation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

secreted proteins are AKA

A

lumenal proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

are secreted proteins inserted into the ER membrane?

A

no they are released into the lumen of the ER

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

membrane proteins are…instead of…

A

inserted into the ER membrane instead of being released into the lumen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

how are integral membrane proteins embedded into the ER mem.

A

by hydrophobic regions that span the phospholipid bilayer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

the hydrophobic regions that embed integral membrane proteins are also known as

A

STS

stop-transfer-sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

the STS are typically

A

α-helical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what are the 3 signal sequences

A
  1. ERSS
  2. STS
  3. ISS
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

the ERSS stands for

A

ER signal sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

the STS stands for

A

stop transfer sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

the ISS stands for

A

internal start sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

list the characteristics of a type I protein

A
  • ERSS @ N-terminus
  • contains signal peptidase cleavage site
  • STS
  • N-terminus at ER lumen
  • C-terminus at cytoplasm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

list the characteristics of a type II protein

A
  • internal ERSS
  • no signal peptidase cleavage site
  • N-terminus at cytoplasm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

list the characteristics of a type III protein

A
  • internal ERSS
  • no signal peptidase cleavage site
  • N-terminus at ER lumen
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

the internal ERSS of a type II protein acts as a

A

start transfer sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

the internal ERSS of a type III proteins acts as a

A

stop transfer sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what happens to proteins that contain a ERSS at the c-terminus?

A

they’re recognized by TRC40 which takes it to the GET1-GET2 receptor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

the positive inside rule states that

A

the more positive side will be found in the cytoplasm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

lumens of ER and Golgi are topologically equivalent to

A

the exterior of the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

list the 5 primary roles of ER lumenal proteins

A
  1. folding of newly translated polypeptides
  2. formation of disulfide bonds
  3. assembly of multi-subunit proteins
  4. N-linked glycosylation
  5. addition of GPI anchors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

chaperones are members of what protein family

A

Hsp70

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

what specific chaperon is used in protein folding

A

BiP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

BiP binds to

A

hydrophobic regions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

BiP uses _______ to assist in folding. what does this molecule do?

A

ATP
- opens & closes BiP binding sites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

what indicates misfolding in a protein

A

too many exposed hydrophobic regions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

misfolded protein is targeted back to the cytosol through a

A

ubiquitin ligase complex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

mechanism for protein breakdown

A

protein is ubiquitylated at the cytosolic side and degraded by a proteasome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

what is required for protein degradation by a proteasome?

A

amino acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

describe N-linked glycosylation

A

glycosylation of the nitrogen of Asn within the consensus sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

what is the consensus sequence for N-glycosylation

A

N-X-S/T

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

where does N-linked glycosylation occur

A

within the ER

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

what are glycosylphosphatidylinositol (GPI) anchors

A

glycolipids containing phosphatidylinositol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

GPI anchors are assembled in the

A

ER membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

GPI anchors are added to the __________ of polypeptides

A

carboxy terminus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

GPI anchors are ultimately exposed to

A

the outside of the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

list 4 other types of ER protein modifications

A
  1. chemical mod. of individual amino acids
  2. proteolytic cleavage
  3. binding to prosthetic groups
  4. formation of multisubunit proteins or molecular complexes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

the smooth ER is a major site for

A

lipid synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

lipid synthesis occurs on the

A

cytosolic side of the membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

what are the 3 main types of lipids

A
  1. phospholipids
  2. glycolipids
  3. cholesterol
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

phospholipids are synthesized from

A

water soluble precursors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

what is the function of flippases

A

catalyze the translocation of phospholipids from the OM to the IM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

transport from the ER to the Golgi is known as what type of transport?

A

anterograde

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

transport from the Golgi to the ER is known as what type of transport?

A

retrograde

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

the Golgi contains NO

A

functional lumenal proteins

57
Q

define cisternae

A

flattened membrane enclosed stacks

58
Q

what are the 3 components to the Golgi

A
  1. cis
  2. medial
  3. trans
59
Q

the cis face is responsible for

A
  • being port entry site
  • protein folding & modifications
60
Q

the cis face is always oriented towards the

A

nucleus

61
Q

the medial Golgi is responsible for

A

most metabolic activities

62
Q

the trans Golgi is responsible for

A
  • being exit port
  • more modification
  • directing cellular traffic
63
Q

how does the trans face of the Golgi direct cellular traffic

A

by acting as the protein sorting and distribution center

64
Q

the Golgi complex is a factory for the

A

processing and sorting transport proteins which have been received from the ER

65
Q

ALL proteins that enter the secretory pathway enter the _________ regardless of their final subcellular destination

A

Golgi

66
Q

what is the c-terminus sequence that targets proteins to be retained in the ER

A

KDEL OR KKXX

67
Q

how do ER proteins return to the ER

A

via a recycling pathway after their transport & modification in the Golgi

68
Q

what are the 2 theories to protein movement once they’ve entered the Golgi

A
  1. ERGIC gets reformed
    - rebuilding cis face
    - degrading trans face
  2. stacks remain stationary
    - proteins move through vesicular transport
69
Q

what 3 things occur in the Golgi apparatus

A
  1. protein processing & modification
  2. lipid metabolism
  3. protein sorting
70
Q

what are the 3 types of protein glycosylation that occurs in the Golgi

A
  1. modification of N-linked oligosaccharides
  2. lysosomal protein modification
  3. o-linked glycosylation
71
Q

in modification of N-linked oligosaccharides what is the role of glycosyltransferases

A

adding sugars

72
Q

in modification of N-linked oligosaccharides what is the role of glycosidases

A

remove the sugars

73
Q

lysosomal protein modification is the

A

addition of mannose-6-phosphate

74
Q

where is mannose-6-phosphate added to

A

the N-linked oligosaccharide of a lysosomal protein

75
Q

what is a signal patch

A

a particular 3-D conformation that targets glycoproteins to lysosomes

76
Q

mannose phosphorylation can ONLY target glycoproteins to lysosomes if they have a

A

signal patch

77
Q

o-linked glycosylation is the addition of a

A

carbohydrate to the O of a serine or threonine

78
Q

lipid metabolism is the

A

synthesis of glycolipids and sphingomyelin

79
Q

glycolipids and sphingomyelin are synthesized from

A

ceramides

80
Q

what is the only non-glycerol phospholipid in membranes

A

sphingomyelins

81
Q

sphingomyelins are formed on the

A

lumenal side of the mem.

82
Q

_____________ cannot be flipped. why?

A

glycolipids
- very hydrophobic

83
Q

glycolipids act as

A

important cell surface markers and signaling molecules

84
Q

glycolipids on only found on what side of the Golgi bilayer

A

lumenal

85
Q

after vesicular transport both sphingomyelin and glycolipids are localized to the

A

exterior half of the plasma mem.

86
Q

processing of proteoglycans refers to the

A

addition of carbohydrate chains and sulfate groups to a polypeptide

87
Q

the proteoglycan chains are composed for what 2 repeating disaccharides

A
  • chondroitin
  • keratin
88
Q

what are the 3 potential destinations from the trans Golgi

A
  1. lysosomes
  2. cell mem.
  3. secretion
89
Q

secreted proteins are considered to be constitutive if they are

A

secreted as soon as they’re made and processed

90
Q

give examples of constitutive secreted proteins

A
  • cytokines from immune cells
  • albumin from the liver
  • adhesion proteins
91
Q

secreted proteins are considered to be regulated if they are

A

secreted out of the cell upon receiving signal from the exterior of the cell

92
Q

give examples of regulated secreted proteins

A
  • neurotransmitters
  • hormones
  • digestive enzymes
93
Q

in polar cells, like epithelial cells, what must be regulated

A

direction of transport & secretion

94
Q

ALL functional proteins retained within the Golgi are associated w/

A

the Golgi mem.

95
Q

what are the 3 characteristics of Golgi-localized proteins

A
  1. short N-terminus facing cytosol
  2. single transmembrane a-helix
  3. large C-terminal domain facing Golgi lumen containing catalytic site
96
Q

what increases progressively from the ER to the plasma

A

the thickness of cellular mem.

97
Q

what are the 2 hypothesis as to what keeps the Golgi proteins associated with the Golgi?

A
  1. membrane proteins move from compartment to compartment until the membrane length exceeds fatty acid tails
  2. Golgi enzymes bind to cytoskeletal proteins preventing their diffusion into transport vesicles
98
Q

define coatamers

A

protein complex that coats membrane bound transport vesicles

99
Q

what are the 3 types of coatamers?

A

-COPI
-COPII
-clathrin

100
Q

COPI is responsible for what type of transport

A

retrograde

101
Q

COPII is responsible for what type of transport

A

anterograde

102
Q

define budding

A

the formation of a transport vesicle at the surface of a membrane-bound compartment

103
Q

define fusion

A

the incorporation of a transport vesicle into a membrane-bound component

104
Q

coat proteins are

A

trimers

105
Q

upon polymerization the trimers forms

A

numerous hexagons

106
Q

complete binding of trimers creates

A

a bent surface with convex and concave sides

107
Q

the growing complex of trimers provides

A

the mechanical force to pull the mem. into a bud

108
Q

as coat proteins assemble around a budding vesicle what is selected?

A

adaptor molecules

109
Q

how is the appropriate cargo incorporated into the vesicle?

A

mem. receptors bind to their respective cargo ligand

110
Q

what is the function of dynamin

A

to pinch off the vesicle during budding

111
Q

what dissociates from the transport vesicle once it enroute to final destination

A

clathrin

112
Q

clathrin coated vesicles can travel

A

both anterograde and retrograde

113
Q

clathrin can carry vesicles between the trans-Golgi network and

A
  • lysosomes
  • endosomes
  • plasma mem.
114
Q

vesicle fusion is mediated by

A

interactions between SNARE proteins on vesicles and target mem.

115
Q

vesicle fusion is regulated by

A

Rab- GTP binding and hydrolysis

116
Q

transport is inhibited by drugs that prevent

A

microtubule polymerization

117
Q

vesicular transport is _______ dependent

A

calcium

118
Q

fusion of what type of secretory vesicles with the plasma mem. is dependent on a specific extracellular signal?

A

regulated

119
Q

the specific extracellular signal triggers the

A

release of calcium within the cell

120
Q

calcium is AKA

A

the second messenger

121
Q

what moves transport vesicles through the cell

A

motor proteins

122
Q

what is considered the ‘highway’ in vesicular transport

A

the cytoskeleton

123
Q

name the two motor proteins

A
  1. dynein
  2. kinesin
124
Q

dynein is responsible for

A

retrograde transport

125
Q

kinesin is responsible for

A

anterograde transport

126
Q

what is the main function of lysosomes

A

to digest material taken in by endocytosis

127
Q

lumenal lysosomal proteins are

A

digestive

128
Q

membrane lysosomal proteins are

A

proton pump

129
Q

mutations in the genes that encode for degradative enzymes found in lysosomes are responsible foe what 2 diseases

A
  1. Gaucher
    2.Tay-sachs
130
Q

the degradative enzymes of a lysosome are active at

A

acidic pH

131
Q

how is the acidic pH maintained within a lysosome

A

by a proton pump

132
Q

what are the degradative enzymes found in lysosomes called

A

acidic hydrolases

133
Q

describe phagocytosis

A

phagosomes take up bacteria, old cells, and debris

134
Q

phagosomes merge w/ __________________ for degradation

A

lysosomes

135
Q

describe autophagy

A

cells’ own components are targeted for digestion

136
Q

autophagy is important in certain stages of

A

embryonic development and programmed cell death

137
Q

what types of cells would you expect to be engaged most heavily in endocytosis?

A
  • macrophages
  • NKC
  • liver cells (glucose & cholesterol intake)
138
Q

which types of cells would you expect to be engaged most heavily in exocytosis?

A
  • neurons
  • pancreatic cells
  • liver cells

Cell Biology (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions