Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

BIOCH 320 > transport-2 > Flashcards

transport-2 Flashcards

(95 cards)

Start Studying
1
Q

what kind of channel is the chloride channel in S. typhimurium

A

anion

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

where are the channels in the chloride channel in S. typhimurium

A

through the center of each subunit, not at interfrace

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

what kind of “mer: structure in the chloride channel in S. typhimurium

A

homodimer

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

how many helices in the chloride channel in S. typhimurium + how are they oriented

A

18 transmembrane alpha helices, tilted relative to membrane

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

what creates the selectivity filter in the chloride channel in S. typhimurium

A

alpha helices (N terminal dipole) and OH containing amino acids(Ser tyr)

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

are there positive in the chloride channel in S. typhimurium and why

A

no because then the anion will just stick to it

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

what do aquaporins do

A

allow for cross-membrane movement of water, excluding other solutes and H+ (H3O+)

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

what kind of “mer” are aquaporins

A

homotetramer

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

what kind of helices in aquaporins

A

multiple transmembrane alpha helices

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

where are water channels formed in aqua porins

A

at the center of each subunit

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

what is the symmetry in aqua porins

A

C4

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

what kind of “mer” are Cl- channels

A

dimer

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

what kind of “mer” are K+ channels

A

tetra

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

where are channels formed in K+

A

between subunits

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

where are channels formed in Cl-

A

within subunits

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

are K+ channels polytopic helical bundles

A

yes

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

are Cl- channels polytopic helical bundles

A

yes

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

what is the movement in aquaporis like

A

proton movement via proton jumping is prevented by Hbonding interactions in the channel

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

what prevents proton jumping in aquaporins

A

H bonding interactions in the channel

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

what does GLUT1 do/what is it

A

passive carrier for D-glucose

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

how many helices in GLUT1

A

12 transmembrane

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

what do lots of the transmembrane helices contain in GLUT1

A

polar amino acids

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

is GLUT1 polytopic

A

yes

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

how many domains in GLUT1 and what are they like

A

2 domains with 6helices each

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
how many aa per turn in helix
3.6
26
what phobicity are transmembrane alpha helices generally
hydrophobic
27
where is the binding site of the solute usually
midway through membrane
28
what are the arrangement of amino acids in amphipathic helices
polar and non polar on opposite faces - non polar towards lipid core - polar towards inside of passage through the center
29
where will non polar regions be in amphipathic helices
oriented towards the lipid core
30
where will polar regions be in amphipathic helices
in the center to create a polar passage
31
does GLUT1 have continuous passage from one side of the membrane to the other and why
no because its a carrier
32
what does binding of glucose to GLUT1 cause
conformational shift leading to binding site being opened to the interior
33
what is GLUT1 transport dependent on
rate of steps in the process (kinetics of binding and conformational rearrangement)
34
what is rate of transport in carries analogous to
michaelis menten enzyme kinetics (similar equation)
35
what is Kt
concentration of colute where Vo=0.5Vmax
36
what is K1 for GLUT1 compared to blood glucose levels
K1 is smaller
37
what does Kt reflect with specificity and GLUT1
specific interactions between the carrier and the OH groups in D-glucose
38
is Kt bigger or smaller with L or D glucose
bigger with L glucose by a lot
39
do calculation question
okie
40
what drives active transport
electrochemical gradient
41
what are the Gt an Gnet for active transport
Gt>0 for at least 1 solute | Gnet< 0 for transport
42
what does negative free energy come from in primary active transport
chemical reaction
43
what does negative free energy come from in secondary active transport
another solute
44
what kind of transport is ATPase
primary active transporters
45
how do ATPases work
hydrolysis of ATP provides energy to move solutes up concentration gradients
46
what kind of conformational changes with ATPases
reversible conformational changes with phosphorylation and dephosphorylation
47
are flippases P-type ATPases
yes
48
what does SERCA stand for
sarcoplasmic and endoplasmic reticulum calcium pumps
49
what type of ATPase is SERCA pump
P-type ATPase
50
what is the role of SERCA pumps
transport of Ca++ our of cytoplasm and into sarcoplasmic reticulim during muscle relaxation
51
are floppases P-type ATPases
no
52
how many domains in SERCA pump
4
53
what are the dimains in SERCA pump
M-transmembrane P-phosphorylation N-nucleotide binding A-actuator
54
how many polypeptides in SERCA pump
1
55
is SERCA pump multipass
yes
56
what is the E1 domain in SERCA pump (where open to)
cytoplasmic face
57
what is the E2 domain in SERCA pump (where open to)
open to exoplasmic face
58
what is the M domain in SERCA pump like +where is it
10 transmembrane helices with 2 Ca++ binding sites near center
59
what is the N domain in SERCA pump like +where is it
cytosolic, ATP binding site
60
what is the P domain in SERCA pump like +where is it
cytosolic, asp side-chain phosphorylated by ATP induces conformational change in M Domain
61
what is the A domain in SERCA pump like +where is it
cytosolic, connects confomational changes in N and P domains to M domain
62
which residue is phosphorylated by ATP In SERCA pump and which domain - what does it become
asp in P domain asparyl phosphate
63
what affinity is the E1 conformation in SERCA + where
high Ca++ affinity in cytosol
64
what affinity is the E2 conformation in SERCA + where
low Ca++ affinity in lumen
65
is the phosphorylation site close to the Ca++ binding site in SERCA
no
66
what state is SERCA in when phosphorylated
E1 to E2
67
what state is SERCA in when unphosphorylated
E2 to E1
68
what is the major facilitator superfamily
multiple families of transporters with relatively low sequence similar but similar predicted topologies
69
what organism classes have major facilitator superfamily
bacteria archaea eukarya
70
how many peptides in major facilitator superfamily + what do they form
single (multipass, helical bundes)
71
how many helices and what do they form in major facilitator superfamily
12-14 helices in 2 semi-symmetrical pairs of 6 or 7 helices
72
what are 2 examples of major facilitator superfamily
lactose transporter and GLUT1
73
what is Kd for calcium bindinf in E1 vs E2 for SERCA
Kd(E1)
74
what kind of transporter is the lactose transporter
2ary active transport
75
what kind of gradient happens in the lactose transporter + which direction
proton gradient is higher on outside than in
76
what direction does the lactose transporter run
proton taken down gradient to bring lactose its gradient
77
what is the E1 for lactose transporter
E1 open to cytoplasmic face
78
what is the E2 for lactose transporter
E2 when open to periplasmic face
79
what maintains the proton gradient in lactose transporter
proton pumps
80
what is affinity for E1 in lactose transporter
low affinity
81
what is affinity for E2 in lactose transporter
high affinity
82
which E does lactose bind to and where is it
E2 outside the cytoplasm
83
which E does lactose release from and where is it
E1 inside the cytoplasm
84
where does lactose bind in lactose permease
between domains near the center
85
how many binding sites for lactose
1
86
how many amino acids in lactose permease
417
87
how many polypeptides in lactose permease
1
88
how many helices in lactose permease
12 transmembrane
89
how many domains in lactose permease
2
90
what is the lactose permease mechanism
binding of lactose and protonation of specific residues in transporter drives a conformational shift -the domains rock, opening binding site to interior where both lactose and proton dissociate
91
what happens if you disrupt the proton gradient or mutations to lactose carrier
it can make it a passive carrier
92
what is a way to inhibit the proton pump in lactose
by CN-
93
what does CN- do to lactose transporter
inhibits proton pump and leads to lactose export | lactose transport down its concentration gradient
94
what does glu or arg mutation in lactose transporter do
uncouples lactose import from the proton gradient | lactose transport down its concentration gradient
95
what determines lactose transport limit
the relative concentration of lactose across the membrane (not saturation!)

BIOCH 320 (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions