Question 1

In voltage-activated channels, preferential ion selectivity for calcium over sodium is governed by which of these factors?

Accepted Answer

A)  Cumulative negative charge of amino acids that line the pore 
B)  An ensemble mix of negative, positive, and neutral amino acids that line the pore 
C)  Glutamine residues at four positions that line the pore 
D)  Aspartate followed by glutamate-that pattern repeated twice-at four key positions that line the pore 
E)  Characteristic features of the P-loop 
A)  Cumulative negative charge of amino acids that line the pore 
B)  An ensemble mix of negative, positive, and neutral amino acids that line the pore 
C)  Glutamine residues at four positions that line the pore 
D)  Aspartate followed by glutamate-that pattern repeated twice-at four key positions that line the pore 
E)  Characteristic features of the P-loop

Question 2

Mutations of which gene in cochlear hair cells causes congenital deafness?

Accepted Answer

A)  TMC1 
B)  TMC2 
C)  KCNQ4 
D)  TMHS 
E)  TMIE 
A)  TMC1 
B)  TMC2 
C)  KCNQ4 
D)  TMHS 
E)  TMIE

Question 3

Which of the following characteristics are similar for Cys-Loop and voltage-activated sodium channels?

Accepted Answer

A)  Relative size and molecular mass of their -subunits 
B)  Relative size and molecular mass of their β-subunits 
C)  The total number of membrane-spanning segments per subunit or domain 
D)  Structure of Cys-Loop receptor subunits and sodium channel domains I-IV 
E)  Primary structure of M2 helices in Cys-Loop receptors and S4 regions of sodium channels 
A)  Relative size and molecular mass of their -subunits 
B)  Relative size and molecular mass of their β-subunits 
C)  The total number of membrane-spanning segments per subunit or domain 
D)  Structure of Cys-Loop receptor subunits and sodium channel domains I-IV 
E)  Primary structure of M2 helices in Cys-Loop receptors and S4 regions of sodium channels

Question 4

Evaluate the notion that hydrophilic amino acids line the pore region of Cys-Loop receptors.

Accepted Answer

Using site-directed mutagenesis to repla

Question 5

Positively charged arginines within the long intracellular loop connecting M3 and M4 dramatically influence channel conductance of which Cys-loop receptor?

Accepted Answer

A)  The glutamate (GluCl) receptor 
B)  The serotonin (5-HT3) receptor 
C)  The γ-aminobutyric acid (GABA
A)  receptor 
D)  The glycine receptor 
E)  ZAC, the zinc receptor 
A)  The glutamate (GluCl) receptor 
B)  The serotonin (5-HT3) receptor 
C)  The γ-aminobutyric acid (GABA
A)  receptor 
D)  The glycine receptor 
E)  ZAC, the zinc receptor

Question 6

What technique allowed scientists to view nAChRs in their open state?

Accepted Answer

A)  Biochemical purification of the receptor from Torpedo 
B)  Plunge freezing 
C)  Site-directed mutagenesis 
D)  Photo-labeling (i.e., ultraviolet flashes) in the presence of Tritiated chloropromazine. 
E)  Cysteine screening followed by MTSEA exposure 
A)  Biochemical purification of the receptor from Torpedo 
B)  Plunge freezing 
C)  Site-directed mutagenesis 
D)  Photo-labeling (i.e., ultraviolet flashes) in the presence of Tritiated chloropromazine. 
E)  Cysteine screening followed by MTSEA exposure

Question 7

Which of the following voltage-activated sodium channels is expressed in cells of both the peripheral and central nervous system?

Accepted Answer

A)  NaV 1.3 
B)  NaV 1.4 
C)  NaV 1.5 
D)  NaV 1.6 
E)  NaV 1.7 
A)  NaV 1.3 
B)  NaV 1.4 
C)  NaV 1.5 
D)  NaV 1.6 
E)  NaV 1.7

Question 8

Create a viable explanation for how calcium activated potassium channels can coexist, and even function cooperatively with voltage-activated calcium channels

Accepted Answer

Voltage-activated calcium channels open

Question 9

Explain the role of KV 7.1 in normal cardiac electrophysiology and cardiac function as well as how mutant KV 7.1 channels with diminished function lead to pathology.

Accepted Answer

K_V 7.1 channels function as cardiac delay

Question 10

Explain the key role played by blocking molecules in discovering the role of the P-loop in voltage-activated ion channels. Given blocking molecule names as part of your answer.

Accepted Answer

In the region linking S5 and S6 of the v

Question 11

With respect to the structure and function of nAChRs, cysteine scanning

Accepted Answer

A)  provided binding sites for tritiated chlorpromazine in the M2 helix. 
B)  refers to scanning for radioactivity of tritiated chlorpromazine after it reacts with cysteines in the M2 helix. 
C)  provided novel binding sites for QX222 in the open channel compared to existing QX222 biding sites in the native receptor. 
D)  revealed that amino acids at 2′, 3′, 6′, 8′, 9′, 10′, 13′, and 16′ lined the pore-forming side of the M2 helix. 
E)  revealed that amino acids at 2′, 6′, and 9′ lined the pore-forming side of the M2 helix. 
A)  provided binding sites for tritiated chlorpromazine in the M2 helix. 
B)  refers to scanning for radioactivity of tritiated chlorpromazine after it reacts with cysteines in the M2 helix. 
C)  provided novel binding sites for QX222 in the open channel compared to existing QX222 biding sites in the native receptor. 
D)  revealed that amino acids at 2′, 3′, 6′, 8′, 9′, 10′, 13′, and 16′ lined the pore-forming side of the M2 helix. 
E)  revealed that amino acids at 2′, 6′, and 9′ lined the pore-forming side of the M2 helix.

Question 12

Genetic mutations affecting this channel can cause persistent burning pain sensations?

Accepted Answer

A)  TRPV1 
B)  KV 7.1 
C)  KV 7.2 and KV 7.3 
D)  KV 7.4 
E)  NaV 1.7 
A)  TRPV1 
B)  KV 7.1 
C)  KV 7.2 and KV 7.3 
D)  KV 7.4 
E)  NaV 1.7

Question 13

Why were electric eels used to discover nAChRs and voltage-activated sodium channels but not voltage-activated potassium channels?

Accepted Answer

A)  nAChRs and voltage-activated sodium channels in eels are similar in structure and function to vertebrate channels so they make a good model to understand channels across phylogeny. 
B)  Electric eels provide an abundance of channels for biochemical purification prior to sequencing and cloning, but voltage-activated potassium channels were cloned using a different strategy. 
C)  A-type voltage-activated potassium channels are not expressed in electric eels, whereas those A-type channels are expressed in invertebrate Drosophila (fruit flies). 
D)  Electric eels are aquatic organisms and thus sensitive to toxins like α-bungarotoxin, TTX, and STX, which assist in biochemical purification. 
E)  Shaker-type mutants were a fortuitous discovery that facilitated biochemical purification of voltage-activated potassium channels thus obviating the need an eel-like model system with abundant channels. 
A)  nAChRs and voltage-activated sodium channels in eels are similar in structure and function to vertebrate channels so they make a good model to understand channels across phylogeny. 
B)  Electric eels provide an abundance of channels for biochemical purification prior to sequencing and cloning, but voltage-activated potassium channels were cloned using a different strategy. 
C)  A-type voltage-activated potassium channels are not expressed in electric eels, whereas those A-type channels are expressed in invertebrate Drosophila (fruit flies). 
D)  Electric eels are aquatic organisms and thus sensitive to toxins like α-bungarotoxin, TTX, and STX, which assist in biochemical purification. 
E)  Shaker-type mutants were a fortuitous discovery that facilitated biochemical purification of voltage-activated potassium channels thus obviating the need an eel-like model system with abundant channels.

Question 14

Make an argument for why foods like red peppers are perceived as hot to our sense of taste.

Accepted Answer

TRPV1 channels detect heat, i.e., their

Question 15

m1 and m2 of KCS channels most closely mimic

Accepted Answer

A)  M1 and M2 of nAChRs. 
B)  S1 and S2 of voltage-activated channels. 
C)  S4 of voltage-activated channels. 
D)  S5 and S6 of voltage-activated channels . 
E)  the extracellular loop connecting S5 and S6 of voltage-activated channels. 
A)  M1 and M2 of nAChRs. 
B)  S1 and S2 of voltage-activated channels. 
C)  S4 of voltage-activated channels. 
D)  S5 and S6 of voltage-activated channels . 
E)  the extracellular loop connecting S5 and S6 of voltage-activated channels.

Question 16

The α-subunit of the voltage-activated potassium channel resembles

Accepted Answer

A)  the α-subunit of the voltage-activated sodium channel. 
B)  the P-loop of the voltage-activated sodium channel. 
C)  domain IV of the voltage-activated sodium channel. 
D)  the α-subunit of the voltage-activated calcium channel. 
E)  the α-subunit typical of a Cys-loop receptor. 
A)  the α-subunit of the voltage-activated sodium channel. 
B)  the P-loop of the voltage-activated sodium channel. 
C)  domain IV of the voltage-activated sodium channel. 
D)  the α-subunit of the voltage-activated calcium channel. 
E)  the α-subunit typical of a Cys-loop receptor.

Question 17

Maximal channel current in nAChRs depends on

Accepted Answer

A)  leucine and valine at 9′, 13′, and 16′ in the M2 helix. 
B)  hydrophobic isoleucine adjacent to lipid or other parts of the protein's secondary or tertiary structure. 
C)  substitution of serine at 6′ in the M2 helix with a more hydrophilic amino acid. 
D)  substitution of serine at 6′ in the M2 helix with a more hydrophobic amino acid. 
E)  hydrophilic serine at 6′ in the M2 helix. 
A)  leucine and valine at 9′, 13′, and 16′ in the M2 helix. 
B)  hydrophobic isoleucine adjacent to lipid or other parts of the protein's secondary or tertiary structure. 
C)  substitution of serine at 6′ in the M2 helix with a more hydrophilic amino acid. 
D)  substitution of serine at 6′ in the M2 helix with a more hydrophobic amino acid. 
E)  hydrophilic serine at 6′ in the M2 helix.

Question 18

Modification of the primary structure of a receptor encapsulates which of the following?

Accepted Answer

A)  Site-directed mutagenesis 
B)  Receptor expression and subunit assembly in Xenopus oocytes 
C)  Electrical recording of single-channel or whole-cell receptor currents 
D)  Ligand binding affinity and pharmacology 
E)  Replacement of polar amino acids with nonpolar ones 
A)  Site-directed mutagenesis 
B)  Receptor expression and subunit assembly in Xenopus oocytes 
C)  Electrical recording of single-channel or whole-cell receptor currents 
D)  Ligand binding affinity and pharmacology 
E)  Replacement of polar amino acids with nonpolar ones

Question 19

Explain the key role of natural high-affinity toxins in discovering and cloning nAChRs and voltage-activated sodium channels? Name the toxins and their targets as a part of your answer.

Accepted Answer

α-bungarotoxin is a highly selective nic

Question 20

Which subunits from vertebrate nAChRs, when their mRNA is expressed in oocytes, may be form homomultimeric channels?

Accepted Answer

A)  Any α2-α10 
B)  Any α2-α6, α10 
C)  Any α7, α8, or α9 
D)  Any β2-β4 
E)  Any α2-α6, α10 with any of β2, β3, or β4 
A)  Any α2-α10 
B)  Any α2-α6, α10 
C)  Any α7, α8, or α9 
D)  Any β2-β4 
E)  Any α2-α6, α10 with any of β2, β3, or β4

Exam 5: Structure of Ion Channels

In voltage-activated channels, preferential ion selectivity for calcium over sodium is governed by which of these factors?

Mutations of which gene in cochlear hair cells causes congenital deafness?

Which of the following characteristics are similar for Cys-Loop and voltage-activated sodium channels?

Evaluate the notion that hydrophilic amino acids line the pore region of Cys-Loop receptors.

Positively charged arginines within the long intracellular loop connecting M3 and M4 dramatically influence channel conductance of which Cys-loop receptor?

What technique allowed scientists to view nAChRs in their open state?

Which of the following voltage-activated sodium channels is expressed in cells of both the peripheral and central nervous system?

Create a viable explanation for how calcium activated potassium channels can coexist, and even function cooperatively with voltage-activated calcium channels

Explain the role of KV 7.1 in normal cardiac electrophysiology and cardiac function as well as how mutant KV 7.1 channels with diminished function lead to pathology.

Explain the key role played by blocking molecules in discovering the role of the P-loop in voltage-activated ion channels. Given blocking molecule names as part of your answer.

With respect to the structure and function of nAChRs, cysteine scanning

Genetic mutations affecting this channel can cause persistent burning pain sensations?

Why were electric eels used to discover nAChRs and voltage-activated sodium channels but not voltage-activated potassium channels?

Make an argument for why foods like red peppers are perceived as hot to our sense of taste.

m1 and m2 of KCS channels most closely mimic

The α-subunit of the voltage-activated potassium channel resembles

Maximal channel current in nAChRs depends on

Modification of the primary structure of a receptor encapsulates which of the following?

Explain the key role of natural high-affinity toxins in discovering and cloning nAChRs and voltage-activated sodium channels? Name the toxins and their targets as a part of your answer.

Which subunits from vertebrate nAChRs, when their mRNA is expressed in oocytes, may be form homomultimeric channels?

Principles of Signaling and Organization

Signaling in the Visual System

Functional Architecture of the Visual Cortex

Ion Channels and Signaling

Ionic Basis of the Resting Potential

Ionic Basis of the Action Potential

Electrical Signaling in Neurons

Ion Transport Across Cell Membranes

Properties and Functions of Neuroglial Cells

Mechanisms of Direct Synaptic Transmission

Indirect Mechanisms of Synaptic Transmission

Release of Neurotransmitters

Neurotransmitters in the Central Nervous System

Transmitter Synthesis, Storage, Transport, and Inactivation

Synaptic Plasticity

The Molecular and Cellular Biology of Synaptic Plasticity

Mechanisms of Extrasynaptic Communication

Autonomic Nervous System

Walking, Flying, and Swimming: Cellular Mechanisms of Sensorimotor Behavior in Invertebrates

Sensory Transduction

Transduction and Transmission in the Retina

Touch, Pain, and Texture Sensation

Auditory and Vestibular Sensation

Constructing Perception

Initiation and Control of Coordinated Muscular Movements

Development of the Nervous System

Critical Periods in Sensory Systems

Regeneration and Repair of Synaptic Connections After Injury

Appendix

Filters

Explain the role of K_V 7.1 in normal cardiac electrophysiology and cardiac function as well as how mutant K_V 7.1 channels with diminished function lead to pathology.

m₁ and m₂ of K_CS channels most closely mimic