Brainscape's Knowledge GenomeTM

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


See full index

BI 338 > Midterm 2 > Flashcards

Midterm 2 Flashcards

1
Q

Are GLUT uniporters reversible?

A

Yes

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

What is faster, protein mediated transport or simple diffusion

A

protein mediated transport

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

What is transport rate limited by

A

number of transporters (Vmax) and transporter affinity (Km) for the ion

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

How many conformational states to uniporters have

A

Two

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

What do ATP Powered pumps do

A

use energy from hydrolysis of the terminal phosphoanhydride bond of ATP

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

What are the 4 classes of ATP powered pumps

A

P-class, V-class, F-class and ABC

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

What are P-class pumps

A

contain 2 identical catalytic alpha subunits that each have an ATP binding site, also contain 2 smaller beta subunits with regulatory functions. Often involved in generating ion gradients across membranes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are V class pumps

A

function to generate the low pH of plant vacuoles and of lysosomes and other acidic vesicles by pumping protons from cytosolic to exoplasmic face of membrane against concentration gradient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are F class pumps

A

are reverse proton pumps, also called ATP synthase

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

T or F: V and F class pumps have a similar structure

A

T

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

What are ABC Superfamily pumps

A

pump a variety of substrates, ex.multidrug resistance proteins
4 core domains: 2 T domains, form passageway for cargo. 2 ATP binding A domains, bind and hydrolyze ATP. 4 independant proteins in bacteria

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

what are some characteristics of the cytosol

A

have a pH of around 7.2, have a high K+, low NA+ and Ca2+

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

protein synthesis requires a high concentration of __ ions

A

K+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

release of __ ions causes muscle relaxation, and pumped by what

A

Ca2+, pumped by P-class ATPase

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

What are some characteristics of P-class Ca2+ ATPase

A

2 binding sites of Ca2+, E1 states have binding sites facing CYTOSOL, E2 binding sites facing EXOPLASMIC face

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

E1 has __ affinity state, __ oxygen atons surround Ca2+ ions in 2 high affinity states

A

high, 7

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

E2 state has __ affinity state, has different orientations and releases __ ions

A

low, Ca2+

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

How can ATPase be converted from E1 to E2

A

by movements of spinning alpha helices

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

P class pumps are phosphorylated on an ____ residue

A

Asp

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

If Km ___ than free concentration, ions will bind

A

less than

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

__ Na+ out, __ K+ in

A

3, 2

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

Which class ATPases usually only pump H+ ions

A

V and F class

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

How do V class H+ ATPases generate electric potential

A

H+ ions are transported in, counter ion (OH-/Cl-) moves left of the cytoplasmic face to create an electric potential. As charge builds, the harder it is to pump H+

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

How do cells address positive charge build up

A

Let in equal number of anions, or move an equal number of different cation out of the lumen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What are some ABC Protein Flippases

A

ABCB1- multidrug export

ABCB4- flips phosphatidylcholine from cytosolic to exoplasmic leaflet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Is ABC CTFR a pump?

A

No, it is a Cl- channel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

T or F: there is an electric potential across the membrane in all cells

A

T

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

What is the average charge of the membrane

A

-60 -> -70mV

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

Transmembrane potential depends on ?

A

ion movement

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

In reality, membranes are permeable to what ions?

A

Na, K , Ca and Cl

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

Animal resting membrane potential depends largely on outward flow of __ ions

A

K+

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

what are nongated channels

A

opening and closing of chaneels not afected by membrane potential or signaling molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

how is the K+ gradient maintained

A

by the Na/K ATPase

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

bacterial, plant and fungal cells are inside- ______ (positive or negative) due to pumping __ out of the cell and leaving behind ____

A

negative, H+, anions

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

structure and chemical nature of a pore _____ (lowers or raises) the activation energy

A

lowers

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

what are the two forces that constitue an electrochemical gradient across a membrane

A

electric potential and ion concentration gradient

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

what type of transport is cotransport

A

secondary active transport

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

what are cotransporters

A

use energy released by ion movement down tis electrochemical gradient to power transport of another molecule or different ion up its concentration gradient

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

why in Na+ a good ion to power the uphill movement of other molecules

A

Na gradient is established by Na/K ATPase, Na reentry down concentration gradient movement goverened by sun of ion concentration gradient and membrane electric potential

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

What is the role of GLUT

A

transports glucose down its concentration gradient

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

when [glucose] in cytosol is greater than in extracellular lumen, how does glucose move

A

up concentration gradient via active transport, facilitated transport when opposite

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

what are the three antiporters that regulate the cytosolic pH and when are they active

A

Na+HCO3-/ Cl- , active at low pH only
Na+/H+, active at low pH only
Cl-/HCO3- , active at high pH only

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

synthesis of secreted proteins begins with ____ _____

A

cytosolic ribosomes

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

what sequence targets proteins to the ER

A

N-terminal signal sequence

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

what are the two key components of targeting a ribsome

A

signal recognition particle (SRP) and its receptor

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

what is the role of SRP

A

a cytolsoic ribonucleoprotein that binds to ER signal sequence forming a large complex. it targets nascant protein ribosome complex to ER by binding to receptor

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

what does the mammalian translocon consist of

A

3 proteins,and Sec61 complex

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

what is the hydrophobic hourglass

A

an hourglass shaped channel that has a helical plug that seals the translocon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

what is signal peptidase

A

transmembrane ER protein that recognizes a sequence of the C-terminal end of the hydrophobic core of the signal peptide and cleaves the chain specifically

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

In most eukaryotes, most secreatory proteins enter the ER by ________ ________

A

cotranslational translocation

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

in yeast, how does post-translational translation occur

A

no SRP or receptor, Sec63 in ER near translocon. molecular chaperone BiP has peptide binding domain and ATPase domain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

T or F: Intergral membrane contain one or more hydrophobic membrane-spanning domains

A

T

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

Where and how are periphrial proteins bound

A

to the side of the membrane by interactions with anchored membrane proteins

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

can membrane proteins flip flop across the membrane?

A

No

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

what is the proteins topology

A

the spatial orientation of proteins

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

how can membrane protein topology be determined

A

by computer programs that identify hydrophobic topogenic segments within the primary amino acid sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

what are the 5 topological classes of intergral membrane proteins

A

Type I, II, III, IV, and tail-anchored proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

which type of intergral membrane proteins have N-terminus of EXOPLASMIC and C-terminus on CYTOPLASMIC FACE

A

Type I and Type III

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

which type of intergral membrane proteins have N-terminus of CYTOPLASMIC face and C-terminus on EXOPLASMIC

A

Type II

60
Q

how are tail-anchored proteins inserted

A

post-translational instertion

61
Q

What are some characteristics of Type I membrane proteins

A

N-terminal signal sequence bound by SRP

stop-transfer anchor squence anchroed in phosphoipid bilayer

62
Q

what are some characteristics of Type II and III membrane proteins

A

Internal signal-anchor equence bound by SRP, positive charged region stays on cytoplasmic face

63
Q

Tail-anchored proteins have a __ - terminal hydroophobic tail

A

C-terminal

64
Q

Type IV-A proteins have N terminus in the ______, while Type IV-B have N terminus in the _______.

A

cyotsol, ER-lumen

65
Q

what are GPI anchored proteins

A

protein portion is synthesized and inserted to the ER membrane, like Type I protein

66
Q

What is GPI transamidase

A

cleaves the precursor protein within the exoplasmic facing domain, covalentaly linked new C-terminus

67
Q

What are the four main modifications in the ER

A
  1. Covalent addition and processing of carbohydrates (glycosylation) in the ER and Golgi
  2. Formation of disulfide bonds in ER
  3. Proper folding of polypeptide chains in ER
  4. Specific proteolytic cleavages in the ER, Golgi and secretory vesicles
68
Q

What is the role of oligosaccharide attachment

A

required for some protein folding, confer stability in some glycoprotiens, play a role in cell to cell adhesion

69
Q

what do disulfide bonds to to many proteins

A

help stabilize the tertirary and quaternary structure of many proteins, form oxidative linkage of sulfhydryl groups

70
Q

what does the prescence of unfolded proteins in the rough ER do

A

increases transcription of genes that encode ER chaperones

71
Q

Modificationso f N-linked oligosaccharides are used to monitor what?

A

folding and quality control

72
Q

what proteins are targeted for transport from ER back to cytosol

A

dislocation-misfolded proteins

73
Q

What is the role of the ERAD complex

A

enables dislocation of misfolded proteins through the membrane

74
Q

what ensures proper forlding or translport in the ER

A

ER chaperones

75
Q

Proteins require oligosaccharides and disulfide bonds via ?

A

ER enzymes

76
Q

What class ATPase used to synthesize ATP?

A

F-class

77
Q

Proteins on mitochrondrial and chloroplast are synthesized in ______

A

ribosomes

78
Q

how many targeting sequences and translocation systems are required for protein import

A

two of each

79
Q

where are precursor proteins synthesized

A

cytosolic ribosomes

80
Q

What are the three energy imports required for protein import to mitochondrial matrix

A
  1. Cytosolic Hsp70
  2. Matrix Hsp70 achored to Tim44 protein
  3. H+ electrochemical gradient
81
Q

many mitochondrial outer membrane proteins have a __ -barrel structure

A

beta

82
Q

Antiparallel strands for _______ transmembrane segments surrounding a central channel

A

hydrophobic

83
Q

How are chloroplast stromal proteins imported

A

rubisco is encoded by chloroplast DNA and transported to chloroplasts from the cytosol. stromal Hsp70 chaperone required to hydrolyze ATP

84
Q

what are thykaloids

A

membranous sacks that contain enzymes for photosynthesis

85
Q

what are the four pathways for transporting proteins from thykaloid to stroma

A

SecA-like
Oxa1-like
SRP-dependant
pH-dependant

86
Q

what are some similarities between the SRP and pH depenadant pathways

A

First imported in an unfolded state, N-terminal cleaved off

87
Q

What happens in SRP-dependant pathway

A

Unfolded protein translocated into thykaloid lumen, chaperones keep protein unfolded, thylakoid targeting sequence removed, then protein folds in thylakoid lumen

88
Q

What happnens in pH- dependant pathway

A

folded protein transfered to thylakoid lumen, has two Arg residues, powered electrochemical gradient across thylakoid membrane, thylakoid targeting sequence cleaved off

89
Q

how are targeting sequences directed in post translational transport

A

through translocons

90
Q

what are peroxisomes

A

small organelles in plants and animals that contain enzymes that oxidize amino and fatty aids, breaking them down for biosynthetic pathways

91
Q

do peroxisomes contain DNA and ribosomes?

A

No

92
Q

How are Peroxisomal proteins targeted

A

requires C-terminal PTS1 sequence, binds to Rex5 receptor and imports folded proteins

93
Q

Are peroxisomal membrane proteins targeted by PTS1

A

no

94
Q

what are luminal peroxisomal proteins

A

synthesized on cytosolic ribosomes, contain c-terminal targeting sequence

95
Q

what is the role of nuclear pores

A

allow movement of mRNAs, tRNAs, and ribosomal subunits out of the nucleus

96
Q

what does the import of nuclear proteins require

A

nuclear localization signals

97
Q

What is a nuclear pore complex

A

many copies of 30 distinct nucleoporins, contains nuclear basket, ions can diffuse passively but not large proteins

98
Q

what are the three types of nucleoporins

A

Structural, membrane and F-G nucleoporins

99
Q

What are structural nucleoporins

A

form scaffold of nuclear pore, 16 copies of Y complex

100
Q

What are membrane nuceleoporins

A

form outer curvature of the nuclear pore

101
Q

what are F-G nucleoporins

A

rich in hydrophobic Phe and Gly residues

102
Q

How are nuclear proteins targeted

A

by Nuclear localization signal (NLS) nad also requires Ran and Nuclear transport receptor (Binds to NLS)

103
Q

nuclear import of proteins- what happens in the cytoplasm

A

importin binds NLS of a cargo protein to form importin-cargo complex and diffuses thorugh NPC by interacting wtih FG nucleoporin

104
Q

nuclear import of proteins- what happens in the nucleoplasm

A

Ran-GDP activated by GF. Releases GDP, binds GTP.

Ran-GTP bidning to importin conformational change that relases NLS-cargo protein

105
Q

nuclear import of proteins- what happens in system recycling

A

Importin-Ran-GTP complex transported back to cytoplasm with filaments of the NPC stimulates Ran hydrolysis of bound GTP

106
Q

How are proteins larger than 40kDa transported into/out of the nucleus?

A

Unidirectional transport though large complex nuclear pore that requires nuclear localization or export signal

107
Q

What is the seceretory pathway of protein sorting

A

distribution of solubule and membrane protein synthesized by rough ER to final destinations at cell surface

108
Q

what is the endocytic pathway of protein sorting

A

vesicles budding from plasma membrane take up soluble extracellular proteins and deliver them to lysosomes via endosomes

109
Q

what are some techniques for studying the secretory pathway

A

SDS-PAGE, temperature sensitive sec mutants, cell-fre assays, can be visualized by flurescence microscopy porducing GFP tagged protein

110
Q

What is the Bradford Assay

A

to determine protein concentration in biological samples

111
Q

what are some pros and cons of the bradford assay

A

adv - accurate and simple, widely used in all biological fields
disadv. - requires irreversable dye binding, linear over a short range, inhibited by some detergents (SDS) , modestly time consuming

112
Q

what is a good model organism for vesicular transport

A

yeast, as secretory pathways are similar in all eukaryotes

113
Q

How does vesicle budding occur

A

initiated by recuritment of GTP-binding
Driven by polymerization of soluble protein
Intergral membrane domains interact with vesicle coat and cargo proteins
coat proteins shed after vesicle released

114
Q

how does vesicle targeting occur

A

by V and t-SNAREs

115
Q

Wht are V-SNAREs

A

incorporated into vesicle membrane during assembly of coat. are accessible after release

116
Q

What are t-SNAREs

A

embedded in target membrane and can interact with conjugate v-SNAREs

117
Q

T or F: all transport vesicles use t and v-SNAREs to fuse

A

T

118
Q

How des vesicle fusion occur

A

provided by interactions of specific v-SNAREs with specific target t-SNAREs, fusion brings bilayers together and releases cargo proteins

119
Q

What are Rab proteins

A

small GTP-bidning proteins that regulate vesicle trafficking and fusion

120
Q

what are the two steps in Rab protein association with a vesicle

A

1- cytosolic Rab-GDP rageted to vesicle membrane-held in place by anchor
2. GEF in membrane converts Rab-GDP to Rab-GTP, which is enabled to bind Rab effectors. GTP hydrolysis releases Rab GDP

121
Q

what must first be removed after it buds off parent membrane in order to expose Rab + v-SNAREs

A

the vesicle coat

122
Q

how are SNAREs inserted into membranes

A

via C-terminal transmembrane chains

123
Q

complexes of v and t-SNAREs are capable of reversable, tight ___-helix bundles

A

four

124
Q

how are SNARE complexes stabilized

A

by arrangement of hydrophobic and charged amino acid residues in heptad residues

125
Q

What are the three types of coated vesicles

A

COP II, COP I and Clathrin

126
Q

What do COPII vesicles do

A

transport proteins form ER to Golgi

127
Q

What do COP I vesicles do

A

transport proteins from Golgi eisternae and cis-Golgi back to ER

128
Q

what do Clathrin coated vesicles do

A

transport proteins from plasma membrane and trans-Golgi to late endosomes

129
Q

What vesicles contain ARF protein

A

COPI and Clathrin

130
Q

What vesicles contain Sar1 protein

A

COPII

131
Q

ARF, SAR1, Ran and Rab are all ______ switch proteins

A

GTPase

132
Q

What is the other function of small GTPases

A

pinching off completed vesicle from parent membrane

133
Q

what do luminal domains do that are on some cargo proteins

A

identify and bring soluble cargo proteins into the vesicle

134
Q

Newly synthesized proteins travel in ____- vesicles from ER to the __-Golgi

A

COPII, Cis-golgi

135
Q

retrograde transport recycles v-SNAREs in ____ vesciles from cis-Golgi to __

A

COPI, ER

136
Q

Yeast cells with mutations in genes for COPII proteins are class __ sec mutants

A

B

137
Q

Sar1-GTP binds to ER memnrane and recruits ____ and _____

A

Sec23 and Sec24

138
Q

Cytosolic domains of COPII contain____

A

di-acidic sorting signal

139
Q

Certain intergral ER membrane proteins also bind cargo proteins in the lumen via _____ ____

A

exoplasmic domain

140
Q

All signal domains interact with ____ in COPII

A

Sec24

141
Q

How do vesicles move?

A

Many move by diffusion in the cytoplasm, microtubules act as railroad tracks to transport vesicles

142
Q

what is retrograde transport

A

COPI vesicles transport between Gogli cisternae and from cis-golgi to rough ER

143
Q

What are some characteristics of ER-resident proteins

A

many soluble proteins that assist in folding and modification of newly synthesized proteins, most carry KDEL sorting sequence

144
Q

what is the role of KDEL receptor

A

acts mainly to retrieve soluble proteins containing KDEL sorting signal at end of C-terminal segment

145
Q

what is cisternal maturation

A

responsbile for anterograde transport thorough the Golgi (cis to trans)

146
Q

What fusion can demonstrate cisternal maturation

A

Fluorescence-tagged fusion

BI 338 (4 decks)

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