Ion Channels

Question 1

metabotropic receptors

Answer 1

Receptors that activate second messenger pathways which can affect physically separate ion channels

Question 1

Each pentameric ligand gated channel subunit has four transmembrane alpha helices (M1 through M4), with ____ assembling around the central pathway.

Answer 1

M2

Question 1

The ion is stabilized within the pore by energetic interactions with the _____.

Answer 1

amino acids forming the pore

Question 2

ionotropic receptors

Answer 2

receptors that are directly coupled to ion channels

Question 2

Ions must be substantially dehydrated before they pass through the _____.

Answer 2

channel pore

Question 3

The pentameric ligand gated channels are either selective for ____, or allow permeation of both sodium and potassium.

Answer 3

chloride

Question 3

Voltage sensing is accomplished by the ____.

Answer 3

S4 helices

Question 4

The reversal of inactivation is called ________.

Answer 4

“removal of inactivation.”

Question 6

Voltage gated channels of the______ have four membrane-spanning domains, each of which contains six alpha helices (S1 through S6).

Answer 6

KV, NaV and CaV families

Question 7

Neurotransmitter receptors are either _____ or ______.

Answer 7

directly coupled to ion channels; activate second messenger pathways

Question 8

For both K(V) and Na(V), gating is controlled by ____.

Answer 8

membrane potential (Vm)

Question 9

______ are structural tetramers.

Answer 9

Aquaporin water channels

Question 10

After the _____ opens, the inactivation gate closes.

Answer 10

activation gate

Question 11

Voltage gated channels of the KV, NaV and CaV families have _____, each of which contains six alpha helices (S1 through S6).

Answer 11

four membrane-spanning domains

Question 12

Pentameric ligand gated channels include ____, ____, _____, and _____.

Answer 12

GABAARs, GlyRs, nAChRs, 5-HT3Rs

Question 13

What do channels select for?

Answer 13

1) size 2) charge 3) dehydration 4) multiple binding sites

Question 14

activation

Answer 14

opening the gate to allow K+ to flow out of the cell

Question 15

After the activation gate opens, the inactivation gate closes, a process called ______.

Answer 15

inactivation

Question 16

Aquaporin water channels are structural ______.

Answer 16

tetramers

Question 17

When the _____ is made positive, the gate rotates to its _____ and K+ ions flow out of the cell.

Answer 17

inside; open position

Question 17

deactivation

Answer 17

closing of the gate to decay the current

Question 17

_______ is accomplished by the S4 helices.

Answer 17

Voltage sensing

Question 18

When the____ is made negative the gate rotates back to the closed position and _____.

Answer 18

inside of the cell; the current decays away

Question 20

Receptors that activate second messenger pathways which can affect physically separate ion channels are called ________.

Answer 20

metabotropic receptors

Question 21

When the inside of the cell is made _____ the gate rotates back to the _____ position and the current decays away.

Answer 21

negative; closed

Question 22

After the activation gate opens, the ______ closes.

Answer 22

inactivation gate

Question 23

The pentameric ligand gated channels are either selective for the permeation of chloride, or allow permeation of both _____ and \_\_\_\_\_.

Answer 23

sodium and potassium

Question 24

The pentameric ligand gated channels are structurally \_\_\_\_\_\_.

Answer 24

heteropentamers

Question 25

\_\_\_\_\_\_\_ have two of its four subunits bind glutamate and the other two bind glycine.

Answer 25

NMDA receptors

Question 26

Ions are ______ in solution by waters of hydration.

Answer 26

energetically stabilized

Question 27

Chloride channels of the CLC family are structural \_\_\_\_.

Answer 27

dimers

Question 28

The S4 helices contain positively-charged Lys or Arg residues at every third position and translocate in response to \_\_\_\_\_.

Answer 28

changes in voltage across the membrane

Question 29

Charge is an important determinant of \_\_\_\_\_\_.

Answer 29

what substances will pass through a channel

Question 30

When the inside of the cell has a ____ potential with respect to the outside, the gate is held in its ____ and the current is zero.

Answer 30

negative; closed position

Question 32

Ions must be _____ before they pass through the channel pore.

Answer 32

substantially dehydrated

Question 33

The ion is stabilized within the pore by _____ with the amino acids forming the pore.

Answer 33

energetic interactions

Question 34

When the inside is made \_\_\_\_\_, the gate rotates to its open position and _____ flow out of the cell.

Answer 34

positive; K+ ions

Question 36

For both ___ and \_\_\_, gating is controlled by membrane potential (Vm).

Answer 36

K(V); Na(V)

Question 37

The ______ are important for stabilizing the resting membrane potential.

Answer 37

CLC chloride channels

Question 38

Ions are energetically stabilized in solution by \_\_\_\_\_.

Answer 38

waters of hydration

Question 39

\_\_\_\_\_ of the CLC family are dimers.

Answer 39

Chloride channels

Question 40

How does lidocaine work?

Answer 40

blocks the sodium/potassium channel from the intracellular side

Question 42

NMDA receptors have\_\_\_\_\_ bind glutamate and the other two bind glycine.

Answer 42

two of its four subunits

Question 44

\_\_\_\_\_\_ of the KV, NaV and CaV families have four membrane-spanning domains, each of which contains \_\_\_\_\_.

Answer 44

Voltage gated channels; six alpha helices (S1 through S6).

Question 45

The S4 helices contain _____ residues at every third position and translocate in response to changes in voltage across the membrane.

Answer 45

positively-charged Lys or Arg

Question 46

\_\_\_\_ is an important determinant of what substances will pass through a channel.

Answer 46

Charge

Question 47

Each pentameric ligand gated channel subunit has \_\_\_\_\_\_, with M2 assembling around the central pathway.

Answer 47

four transmembrane alpha helices (M1 through M4)

Question 48

NMDA receptors have two of its four subunits bind _____ and the other two bind \_\_\_\_\_.

Answer 48

glutamate; glycine

Question 49

Receptors that are directly coupled to ion channels are called \_\_\_\_\_\_\_\_\_.

Answer 49

ionotropic receptors

Question 50

\_\_\_\_\_ are either directly coupled to ion channels or activate second messenger pathways.

Answer 50

Neurotransmitter receptors

Question 51

Which are the positive/basic amino acid residues?

Answer 51

lysine and arginine

Question 52

When the _____ has a negative potential, the gate is held in its closed position and the current is \_\_\_\_.

Answer 52

inside of the cell; zero

Question 53

Which are the negative/acidic amino acid residues?

Answer 53

glutamate or aspartate

Question 54

The CLC chloride channels are important for \_\_\_\_\_\_.

Answer 54

stabilizing the resting membrane potential