Verified Test Bank Chapter.4 Ion Channels And Signaling - From Neuron to Brain 6e | Test Bank Martin by A. Robert Martin. DOCX document preview.
Chapter 4: Ion Channels and Signaling
Test Bank
Type: multiple choice question
Title: Chapter 04 Question 01
1. How thick is the plasma membrane of a cell?
Feedback: Subhead: Properties of Ion Channels
Learning Objective: Explain what ion channels are and describe their general physical features.
Bloom’s Level: 1. Remembering
a. 0.6 nm
b. 2 nm
c. 6 nm
d. 20 nm
e. 600 nm
Type: multiple choice question
Title: Chapter 04 Question 02
2. Plasma membrane lipid molecules
Feedback: Subhead: Properties of Ion Channels
Learning Objective: Explain what ion channels are and describe their general physical features.
Bloom’s Level: 2. Understanding
a. allow ions to diffuse across the membrane against their concentration gradient.
b. are entirely hydrophobic.
c. allow ions to diffuse across the membrane down their concentration gradient.
d. are arranged with their polar, hydrophilic heads facing outward and their hydrophobic tails extending to the middle of the layer.
e. are arranged with their polar, hydrophilic heads facing inward to the middle of the layer and their hydrophobic tails extending outward.
Type: multiple choice question
Title: Chapter 04 Question 03
3. The “selectivity filter” in an ion channel is most accurately described as a part of the pore that
Feedback: Subhead: Properties of Ion Channels
Learning Objective: Explain what ion channels are and describe their general physical features.
Bloom’s Level: 2. Understanding
a. contains a ring of uncharged residues that interact with specific ions.
b. contains a ring of charged residues that interact with specific ions.
c. contains a ring of charged residues that change conformation to either open or close access through the pore for ions.
d. contains a ring of uncharged residues that change conformation to either open or close access through the pore for ions.
e. interacts with lipids.
Type: multiple choice question
Title: Chapter 04 Question 04
4. How can protein molecules be positioned in the plasma membrane?
Feedback: Subhead: Properties of Ion Channels
Learning Objective: Explain what ion channels are and describe their general physical features.
Bloom’s Level: 2. Understanding
a. Protein molecules are buried in the lipid bilayer of the membrane and are not exposed to either the cytoplasm of the extracellular space.
b. All protein molecules completely span the membrane and face both the cytoplasm and the extracellular space.
c. Protein molecules can face only the extracellular side, only the cytoplasm, or span the membrane completely and face both the extracellular side and the cytoplasm.
d. Protein molecules in the membrane only face the cytoplasm.
e. Protein molecules in the membrane only face the extracellular space.
Type: multiple choice question
Title: Chapter 04 Question 05
5. The channel “gate” is best described as a part of the channel
Feedback: Subhead: Properties of Ion Channels
Learning Objective: Explain what ion channels are and describe their general physical features.
Bloom’s Level: 2. Understanding
a. pore that contains a ring of uncharged residues that interact with specific ions.
b. pore that contains a ring of charged residues that interact with specific ions.
c. structure that can change shape to either close or open the access through the channel pore.
d. structure that responds directly to changes in voltage across the plasma membrane.
e. pore that aids in stripping water from hydrated ions before they enter the pore.
Type: multiple choice question
Title: Chapter 04 Question 06
6. What is a cation?
Feedback: Subhead: Properties of Ion Channels
Learning Objective: Explain how ion channels regulate the flow of ions into and out of cells.
Bloom’s Level: 1. Remembering
a. A negatively charged particle
b. An uncharged particle
c. A positively charged particle
d. A negatively charged amino acid residue
e. A positively charged amino acid residue
Type: multiple choice question
Title: Chapter 04 Question 07
7. Channel “activation” is a(n)
Feedback: Subhead: Properties of Ion Channels
Learning Objective: Explain how ion channels regulate the flow of ions into and out of cells.
Bloom’s Level: 2. Understanding
a. increase in the channel mean open time.
b. decrease in the channel mean open time.
c. increase in the frequency of channel opening.
d. decrease in the frequency of channel opening.
e. increase in the frequency of channel opening and the channel mean open time.
Type: multiple choice question
Title: Chapter 04 Question 08
8. What is an anion?
Feedback: Subhead: Properties of Ion Channels
Learning Objective: Explain how ion channels regulate the flow of ions into and out of cells.
Bloom’s Level: 1. Remembering
a. A negatively charged particle
b. An uncharged particle
c. A positively charged particle
d. A negatively charged amino acid residue
e. A positively charged amino acid residue
Type: multiple choice question
Title: Chapter 04 Question 09
9. Hyperpolarization occurs when the membrane potential
Feedback: Subhead: Properties of Ion Channels
Learning Objective: Explain how ion channels regulate the flow of ions into and out of cells.
Bloom’s Level: 1. Remembering
a. does not change.
b. displays rectification.
c. becomes more negative.
d. changes direction.
e. becomes more positive.
Type: multiple choice question
Title: Chapter 04 Question 10
10. Depolarization occurs when the membrane potential
Feedback: Subhead: Properties of Ion Channels
Learning Objective: Explain how ion channels regulate the flow of ions into and out of cells.
Bloom’s Level: 1. Remembering
a. does not change.
b. displays rectification.
c. becomes more negative.
d. changes direction.
e. becomes more positive.
Type: multiple choice question
Title: Chapter 04 Question 11
11. When a large molecule binds to and physically obstructs the pore of a channel, it is called
Feedback: Subhead: Properties of Ion Channels
Learning Objective: Explain how ion channels regulate the flow of ions into and out of cells.
Bloom’s Level: 2: Understanding
a. mechanoreception.
b. ligand gating.
c. an open channel block.
d. channel deactivation.
e. a sensitivity filter.
Type: multiple choice question
Title: Chapter 04 Question 12
12. Deactivation occurs when a
Feedback: Subhead: Properties of Ion Channels
Learning Objective: Explain how ion channels regulate the flow of ions into and out of cells.
Bloom’s Level: 1. Remembering
a. channel opens in response to a stimulus.
b. ligand-gated ion channels closes in the continued presence of the stimulus to open.
c. voltage-gated ion channel closes in the continued presence of the stimulus to open.
d. channel closes after the stimulus to open has been removed.
e. channel does not respond to a stimulus.
Type: multiple choice question
Title: Chapter 04 Question 13
13. Permeability can be defined as
Feedback: Subhead: Properties of Ion Channels
Learning Objective: Explain how ion channels regulate the flow of ions into and out of cells.
Bloom’s Level: 2. Understanding
a. the ease with which ions can move across the membrane.
b. the voltage-dependence of activation of an ion channel.
c. the mean open time of a channel.
d. the equilibrium potential of an ion.
e. simple diffusion of ions down their concentration gradient.
Type: multiple choice question
Title: Chapter 04 Question 14
14. Channels can be induced to open based on
Feedback: Subhead: Properties of Ion Channels
Learning Objective: Compare and contrast voltage-activated channels, mechanoreceptor channels, and ligand-activated channels.
Bloom’s Level: 2. Understanding
a. only the voltage across the membrane.
b. only the effects of membrane stretch on the channel.
c. only the effects of ligand binding to the channel.
d. only the effects of either voltage across the membrane, membrane stretch, or ligand binding, but not more than one of these.
e. the effects of voltage across the membrane, membrane stretch, ligand binding, or a mixture of these influences.
Type: multiple choice question
Title: Chapter 04 Question 15
15. In the continued presence of the stimulus to open, after opening initially, some voltage-gated channels will close and remain closed for the remainder of the stimulus. This is called
Feedback: Subhead: Properties of Ion Channels
Learning Objective: Compare and contrast voltage-activated channels, mechanoreceptor channels, and ligand-activated channels.
Bloom’s Level: 1. Remembering
a. activation.
b. inactivation.
c. deactivation.
d. contraction.
e. desensitization.
Type: multiple choice question
Title: Chapter 04 Question 16
16. In the continued presence of the stimulus to open, after opening initially, some ligand-gated channels will close and remain closed for the remainder of the stimulus. This is called
Feedback: Subhead: Properties of Ion Channels
Learning Objective: Compare and contrast voltage-activated channels, mechanoreceptor channels, and ligand-activated channels.
Bloom’s Level: 1. Remembering
a. activation.
b. inactivation.
c. deactivation.
d. contraction.
e. desensitization.
Type: multiple choice question
Title: Chapter 04 Question 17
17. What is the diameter of the tip of a microelectrode?
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: Describe the technique of intracellular recording with microelectrodes and the properties of membrane channels that it can measure.
Bloom’s Level: 1. Remembering
a. 1-3 micrometers
b. 1 millimeter
c. 10 micrometers
d. 100 micrometers
e. less than 0.5 micrometers
Type: multiple choice question
Title: Chapter 04 Question 18
18. Microelectrode recording is a method commonly used for accurate measurements of
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: Describe the technique of intracellular recording with microelectrodes and the properties of membrane channels that it can measure.
Bloom’s Level: 2. Understanding
a. ionic currents through channels.
b. voltage across a cell membrane.
c. the number of channels expressed by a cell.
d. the equilibrium potential of a channel.
e. the mean open time of a channel.
Type: multiple choice question
Title: Chapter 04 Question 19
19. If an experimenter wants to apply a neurotransmitter molecule in the middle of a recording session using a patch clamp experiment to measure the effects of the neurotransmitter on ligand-gated ion channels, which experimental approach in most commonly used?
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: List three of the recording configurations that can be made with patch clamp methods and describe the advantages of each one.
Bloom’s Level: 5. Evaluating
a. Microelectrode recording
b. Intracellular recording
c. Cell-attached patch clamp
d. Outside-out patch clamp
e. Inside-out patch clamp
Type: multiple choice question
Title: Chapter 04 Question 20
20. If an experimenter wants to apply a cytoplasmic molecule in the middle of a recording session using a patch clamp experiment to measure the effects of this ligand on ion channels, which experimental approach in most commonly used?
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: List three of the recording configurations that can be made with patch clamp methods and describe the advantages of each one.
Bloom’s Level: 5. Evaluating
a. Microelectrode recording
b. Whole-cell patch clamp
c. Cell-attached patch clamp
d. Outside-out patch clamp
e. Inside-out patch clamp
Type: multiple choice question
Title: Chapter 04 Question 21
21. The “inside-out” patch clamp technique
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: List three of the recording configurations that can be made with patch clamp methods and describe the advantages of each one.
Bloom’s Level: 5. Evaluating
a. allows the experimenter to easily change the solution bathing the inside surface of the membrane patch during the recording and study the activity of single voltage-gated channel currents.
b. allows the experimenter to easily change the solution bathing the outside surface of the membrane patch during the recording and study the activity of single voltage-gated channel currents.
c. does not allow the experimenter to change the solution on either side of the membrane patch, but you can study the activity of single voltage-gated currents.
d. allows the experimenter to easily change the solution bathing the inside surface of the membrane patch during the recording and study the summed activity of all voltage-gated channels in the cell (macroscopic current).
e. allows the experimenter to easily change the solution bathing the outside surface of the membrane patch during the recording and study the summed activity of all voltage-gated channels in the cell (macroscopic current).
Type: multiple choice question
Title: Chapter 04 Question 22
22. The “outside-out” patch clamp technique
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: List three of the recording configurations that can be made with patch clamp methods and describe the advantages of each one.
Bloom’s Level: 5. Evaluating
a. allows the experimenter to easily change the solution bathing the inside surface of the membrane patch during the recording and study the activity of single voltage-gated channel currents.
b. allows the experimenter to easily change the solution bathing the outside surface of the membrane patch during the recording and study the activity of single voltage-gated channel currents.
c. does not allow the experimenter to change the solution on either side of the membrane patch, but you can study the activity of single voltage-gated currents.
d. allows the experimenter to easily change the solution bathing the inside surface of the membrane patch during the recording and study the summed activity of all voltage-gated channels in the cell (macroscopic current).
e. allows the experimenter to easily change the solution bathing the outside surface of the membrane patch during the recording and study the summed activity of all voltage-gated channels in the cell (macroscopic current).
Type: multiple choice question
Title: Chapter 04 Question 23
23. The “whole cell” patch clamp technique
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: List three of the recording configurations that can be made with patch clamp methods and describe the advantages of each one.
Bloom’s Level: 5. Evaluating
a. allows the experimenter to easily change the solution bathing the inside surface of the cell during the recording and study the activity of single voltage-gated channel currents.
b. allows the experimenter to easily change the solution bathing the outside surface of the cell during the recording and study the activity of single voltage-gated channel currents.
c. does not allow the experimenter to change the solution on either side of the cell, but you can study the summed activity of all voltage-gated channels in the cell (macroscopic current).
d. allows the experimenter to easily change the solution bathing the inside surface of the cell during the recording and study the summed activity of all voltage-gated channels in the cell (macroscopic current).
e. allows the experimenter to easily change the solution bathing the outside surface of the cell during the recording and study the summed activity of all voltage-gated channels in the cell (macroscopic current).
Type: multiple choice question
Title: Chapter 04 Question 24
24. The “cell-attached” patch clamp technique
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: List three of the recording configurations that can be made with patch clamp methods and describe the advantages of each one.
Bloom’s Level: 5. Evaluating
a. allows the experimenter to easily change the solution bathing the inside surface of the membrane patch during the recording and study the activity of single voltage-gated channel currents.
b. allows the experimenter to easily change the solution bathing the outside surface of the membrane patch during the recording and study the activity of single voltage-gated channel currents.
c. does not allow the experimenter to change the solution on either side of the membrane patch, but you can study the activity of single voltage-gated currents.
d. allows the experimenter to easily change the solution bathing the inside surface of the membrane patch during the recording and study the summed activity of all voltage-gated channels in the cell (macroscopic current).
e. allows the experimenter to easily change the solution bathing the outside surface of the membrane patch during the recording and study the summed activity of all voltage-gated channels in the cell (macroscopic current).
Type: multiple choice question
Title: Chapter 04 Question 25
25. What is the diameter of the tip of a pipette used for patch clamp recording?
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: List three of the recording configurations that can be made with patch clamp methods and describe the advantages of each one.
Bloom’s Level: 1. Remembering
a. Less than 0.5 micrometers
b. 1 micrometer
c. 1 millimeter
d. 100 micrometers
e. 10 millimeters
Type: multiple choice question
Title: Chapter 04 Question 26
26. The conductance of a channel depends on which two factors?
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: Define channel conductance and name the two factors on which it depends.
Bloom’s Level: 3. Applying
a. The voltage across the plasma membrane and the concentration of ions
b. Channel permeability and the voltage across the plasma membrane
c. The mean open time of the channel and the concentration of ions
d. Channel permeability and the concentration of the ions
e. The mean open time of the channel and the channel permeability
Type: multiple choice question
Title: Chapter 04 Question 27
27. Conductance characteristics of a channel can be specified precisely by determining
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: Define channel conductance and name the two factors on which it depends.
Bloom’s Level: 3. Applying
a. a slope conductance.
b. a chord conductance.
c. a complete current–voltage relation and by specifying the ionic conditions under which it was obtained.
d. an averaging of the slope conductance and the chord conductance.
e. the driving force.
Type: multiple choice question
Title: Chapter 04 Question 28
28. Driving force on a specific ion is
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: Define channel conductance and name the two factors on which it depends.
Bloom’s Level: 1. Remembering
a. the voltage-dependence of activation for that ion channel.
b. equal to the voltage across the membrane minus the equilibrium potential for the ion.
c. equal to the equilibrium potential for the ion.
d. equal to the concentration gradient across the membrane for the ion.
e. equal to the conductance through channels for the ion.
Type: multiple choice question
Title: Chapter 04 Question 29
29. Under which of the following conditions would the current–voltage relation for a channel be nonlinear?
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: Explain what equilibrium potential is and what it depends on.
Bloom’s Level: 5. Evaluating
a. When the voltage across the plasma membrane is very negative
b. When the ion concentrations on either side of the channel are symmetrical, or because the channel itself is nonrectifying
c. When the ion concentrations on either side of the channel are not symmetrical, or because the channel itself is rectifying
d. When the equilibrium potential for the channel is at zero millivolts
e. When the mean open time of the channel randomly varies
Type: multiple choice question
Title: Chapter 04 Question 30
30. If the potassium ion concentration is 3 mM outside and 88 mM in the cytoplasm, and potassium selective channels open with the membrane potential at -85 mV, which will occur?
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: Explain what equilibrium potential is and what it depends on.
Bloom’s Level: 4. Analyzing
a. The net flux of potassium ions will be inward.
b. The net flux of potassium ions will be outward.
c. There will be no net flux of potassium ions—it will be equal in and out.
d. There will be no movement of potassium ions across the membrane.
e. Potassium channels will inactivate.
Type: multiple choice question
Title: Chapter 04 Question 31
31. If the potassium ion concentration is 3 mM outside and 88 mM in the cytoplasm, and potassium selective channels open with the membrane potential at -95 mV, which will occur?
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: Explain what equilibrium potential is and what it depends on.
Bloom’s Level: 4. Analyzing
a. The net flux of potassium ions will be inward.
b. The net flux of potassium ions will be outward.
c. There will be no net flux of potassium ions—it will be equal in and out.
d. There will be no movement of potassium ions across the membrane.
e. Potassium channels will inactivate.
Type: multiple choice question
Title: Chapter 04 Question 32
32. If the sodium ion concentration is 130 mM outside and 12 mM in the cytoplasm, and sodium selective channels open with the membrane potential at +80 mV, which will occur?
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: Explain what equilibrium potential is and what it depends on.
Bloom’s Level: 4. Analyzing
a. The net flux of sodium ions will be inward.
b. The net flux of sodium ions will be outward.
c. There will be no net flux of sodium ions—it will be equal in and out.
d. There will be no movement of sodium ions across the membrane.
e. Sodium channels will inactivate.
Type: multiple choice question
Title: Chapter 04 Question 33
33. Increasing the concentration of sodium ions on the outside of the membrane (for example, increasing sodium outside from 130 to 200 mM)
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: Explain what equilibrium potential is and what it depends on.
Bloom’s Level: 5. Evaluating
a. does not change the sodium ion equilibrium potential.
b. makes the sodium ion equilibrium potential more negative.
c. makes the sodium ion equilibrium potential more positive.
d. changes the mean open time of sodium channels.
e. changes the electrostatic charges within the pore of the channel.
Type: multiple choice question
Title: Chapter 04 Question 34
34. What governs the movement of ions through channels in the plasma membrane?
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: Explain what equilibrium potential is and what it depends on.
Bloom’s Level: 2. Understanding
a. Ions move through such channels passively, driven by concentration gradients and by the electrical potential across the membrane.
b. Ions move through channels actively, driven by the energy provided by ATP.
c. Ions move through channels passively, driven only by the concentration gradient.
d. Ions move through channels passively, driven only by the electrical potential across the membrane.
e. Ions move through channels actively, driven by the energy provided by GTP.
Type: multiple choice question
Title: Chapter 04 Question 35
35. The equilibrium potential depends on
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: Explain what equilibrium potential is and what it depends on.
Bloom’s Level: 3. Applying
a. the open state of the channel.
b. the ion concentrations on either side of the membrane.
c. the mechanism for ion permeation through the channel.
d. whether the channel is inactivated.
e. the number of pathways for current flux.
Type: multiple choice question
Title: Chapter 04 Question 36
36. At the equilibrium potential
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: Explain what equilibrium potential is and what it depends on.
Bloom’s Level: 2. Understanding
a. the concentration gradient is zero.
b. there is no movement of ions across the plasma membrane.
c. there is an exact balance between forces of the concentration gradient and the electrical potential gradient.
d. there is a maximum movement of ions across the plasma membrane.
e. the electrical potential gradient is zero.
Type: multiple choice question
Title: Chapter 04 Question 37
37. When membrane potential is at the equilibrium potential for an ion, there is/are
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: Explain what equilibrium potential is and what it depends on.
Bloom’s Level: 2. Understanding
a. an inward net movement of ions.
b. no net movement of ions across the membrane (equal in and out).
c. an outward net movement of ions.
d. no movement of ions in either direction (in or out).
e. equal numbers of the permeant ion inside and outside the cell.
Type: multiple choice question
Title: Chapter 04 Question 38
38. Increasing the concentration of potassium ions on the outside of the membrane (for example, increasing potassium outside from 3 to 20 mM)
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: Explain what equilibrium potential is and what it depends on.
Bloom’s Level: 6. Creating
a. does not change the potassium ion equilibrium potential.
b. makes the potassium ion equilibrium potential more negative.
c. makes the potassium ion equilibrium potential more positive.
d. changes the mean open time of potassium channels.
e. change the electrostatic charges within the pore of the channel.
Type: multiple choice question
Title: Chapter 04 Question 39
39. If the potassium ion concentration is 3 mM outside and 88 mM in the cytoplasm, and potassium selective channels open with the membrane potential at -30 mV, which will occur?
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: Explain what equilibrium potential is and what it depends on.
Bloom’s Level: 4. Analyzing
a. The net flux of potassium ions will be inward.
b. The net flux of potassium ions will be outward.
c. There will be no net flux of potassium ions—it will be equal in and out.
d. There will be no movement of potassium ions across the membrane.
e. Potassium channels will inactivate
Type: multiple choice question
Title: Chapter 04 Question 40
40. If the sodium ion concentration is 130 mM outside and 12 mM in the cytoplasm, and sodium selective channels open with the membrane potential at -30 mV, which will occur?
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: Explain what equilibrium potential is and what it depends on.
Bloom’s Level: 4. Analyzing
a. The net flux of sodium ions will be inward.
b. The net flux of sodium ions will be outward.
c. There will be no net flux of sodium ions—it will be equal in and out.
d. There will be no movement of sodium ions across the membrane.
e. Sodium channels will inactivate.
Type: multiple choice question
Title: Chapter 04 Question 41
41. The equilibrium potential for a channel can be described as proportional to the
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: Explain what equilibrium potential is and what it depends on.
Bloom’s Level: 1. Remembering
a. difference between the concentration inside the cell and outside the cell.
b. between the logarithms of the concentration inside the cell and outside the cell.
c. addition of the logarithms of the concentration inside the cell and outside the cell.
d. addition of the concentration inside the cell and outside the cell.
e. multiplication of the logarithms of the concentration inside the cell and outside the cell.
Type: multiple choice question
Title: Chapter 04 Question 42
42. A “rectifiying” channel
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: Name the relationship given by the Nernst equation.
Bloom’s Level: 2. Understanding
a. does not conduct ions because the pore is closed.
b. conducts ions equally in both directions.
c. is better at conducting ions in one direction than the other.
d. inactivates rapidly.
e. deactivates rapidly.
Type: multiple choice question
Title: Chapter 04 Question 43
43. Based on the Nernst equation, if the concentration of sodium outside was 130 mM and the concentration of sodium in the cytoplasm was 12 mM, what is the sodium equilibrium potential?
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: Name the relationship given by the Nernst equation.
Bloom’s Level: 4. Analyzing
a. -85 mV
b. -30 mV
c. 0 mV
d. +30 mV
e. +60 mV
Type: multiple choice question
Title: Chapter 04 Question 44
44. Based on the Nernst equation, if the concentration of potassium outside was 3 mM and the concentration of sodium in the cytoplasm was 88 mM, what is the potassium equilibrium potential?
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: Name the relationship given by the Nernst equation.
Bloom’s Level: 4. Analyzing
a. -85 mV
b. -30 mV
c. 0 mV
d. +30 mV
e. +60 mV
Type: multiple choice question
Title: Chapter 04 Question 45
45. Eyring rate theory models of ion permeation
Feedback: Subhead: Measurement of Single Channel Currents
Learning Objective: Explain how ions actually move through channels.
Bloom’s Level: 2. Understanding
a. are based on ion diffusion only.
b. are based on the contribution of electrostatic charges in the pore only on the rate of flux.
c. are based on the contribution of electrostatic charges in the pore only on ion selectivity.
d. incorporate the effects of electrostatic charges in the pore on ion selectivity and the rate of flux.
e. incorporate the effects of electrostatic charges in the pore and the voltage across the membrane.
Type: multiple choice question
Title: Chapter 04 Question 46
46. Ion permeation can be described as
Feedback: Subhead: Properties of Ion Channels
Subhead: Measurement of Single Channel Currents
Learning Objective: Explain how ions actually move through channels.
Bloom’s Level: 3. Applying
a. simple diffusion of ions down their concentration gradient.
b. active transport of ions against their concentration gradient.
c. facilitated transport of ions against their concentration gradient.
d. hopping or jumping of ions along electrostatic binding sites in the pore driven by the concentration gradient and the charge across the membrane.
e. hopping or jumping of ions along electrostatic binding sites in the pore driven by the concentration gradient.
Type: essay/short answer question
Title: Chapter 04 Question 47
47. Even though channels have a mean open time, what causes the measured openings of the channel to vary randomly around this mean?
Feedback: All large molecules, like proteins, are inherently dynamic. At room temperature, chemical bonds stretch and relax, and twist and wave around their equilibrium positions. The “atomic trembling” that results from this random motion can lead to larger and slower changes in conformation of the molecule that can result in the opening of the channel for a brief period of time that randomly varies around the mean open time.
Subhead: Properties of Ion Channels
Learning Objective: Explain what ion channels are and describe their general physical features.
Bloom’s Level: 2. Understanding
Type: essay/short answer question
Title: Chapter 04 Question 48
48. For two ions that have almost exactly the same radius (sodium and calcium), how can voltage-gated ion channels be selectively permeable to one or the other?
Feedback: The selectivity of an ion channel to particular ions is regulated by charged amino acid residues in the channel pore that selectively bind to particular ions. For example, even though sodium and calcium ions are nearly the same size and could physically fit through a pore of a calcium channel, when both ions are present, the calcium ions will selectively pass through the pore because there are calcium ion binding sites inside the pore of calcium selective channels.
Subhead: Properties of Ion Channels
Learning Objective: Explain what ion channels are and describe their general physical features.
Bloom’s Level: 6. Creating
Type: essay/short answer question
Title: Chapter 04 Question 49
49. How do channels in the plasma membrane cause a depolarization of membrane potential?
Feedback: Depolarization occurs when a channel selective for positively charged ions opens and those positively charged ions pass through the channel into the cell cytoplasm based on their driving force. This makes the inside of the cell membrane more positive as compared to the outside, creating a depolarization in membrane potential.
Subhead: Properties of Ion Channels
Learning Objective: Explain how ion channels regulate the flow of ions into and out of cells.
Bloom’s Level: 4. Analyzing
Type: essay/short answer question
Title: Chapter 04 Question 50
50. What does the “gate” on an ion channel do?
Feedback: A gate is the part of the ion channel protein structure that opens and closes to control ion movement through the channel. When the channel is exposed to the stimulus that normally opens the channel, there is a conformational change in the channel protein that changes the shape of the protein within the pore region to open the channel. Those amino acid residues that change conformation to open the channel are called the “gate.”
Subhead: Properties of Ion Channels
Learning Objective: Explain how ion channels regulate the flow of ions into and out of cells.
Bloom’s Level: 2. Understanding
Type: essay/short answer question
Title: Chapter 04 Question 51
51. Compare and contrast voltage-activated channels, mechanocreptor channels, and ligand-activated channels.
Feedback: All of these types of channels enable permeability of the cell membrane. Voltage-activated channels respond to changes in the membrane potential. Mechanoreceptors respond to mechanical distortion, such as membrane stretching. Ligand-activated channels respond to chemical agonists that attach to binding sites on the channel protein.
Subhead: Properties of Ion Channels
Learning Objective: Compare and contrast voltage-activated channels, mechanoreceptor channels, and ligand-activated channels.
Bloom’s Level: 2: Understanding
Type: essay/short answer question
Title: Chapter 04 Question 52
52. When you compare the current across a muscle cell membrane before and after applying acetylcholine, you notice that acetylcholine causes to a large inward current and that there is also an increase in the baseline fluctuations (or “noise”) in the recorded current. What causes this “noise”?
Feedback: Acetylcholine released from the presynaptic nerve terminal opens a large number of ligand-gated channels in the postsynaptic muscle membrane. These channels allow ions to pass through each single ligand-gated ion channel. The characteristics of these channel openings (amplitude and frequency) create a noise in the resulting current. The amplitude of fluctuations in the noise reflect the amplitude of single channel openings, while the frequency of such noise is proportional to the frequency of channel opening.
Subhead: Measurement of Single Channel Currents
Learning Objective: Describe the technique of intracellular recording with microelectrodes and the properties of membrane channels that it can measure.
Bloom’s Level: 2. Understanding
Type: essay/short answer question
Title: Chapter 04 Question 53
53. Briefly explain the principle of “noise analysis.”
Feedback: Noise analysis uses the properties of the noise in a whole cell current recording while channels are opening and closing to estimate the single channel current size and mean open time. If the single-channel currents are relatively large, then the size of the noise fluctuations will be large as well, while if single channel currents are small, the size of the noise fluctuations will be small. If channels open for a relatively long time they will produce low-frequency noise, while if they open only briefly they will produce higher frequency noise.
Subhead: Measurement of Single Channel Currents
Learning Objective: Describe the technique of intracellular recording with microelectrodes and the properties of membrane channels that it can measure.
Bloom’s Level: 2. Understanding
Type: essay/short answer question
Title: Chapter 04 Question 54
54. Why is a high resistance seal (a “giga-seal”) required to perform patch clamp recordings?
Feedback: When ions move between the cell cytoplasm and the extracellular solution, these ions move along the path of least resistance. The resistance across the cell membrane is determined by the number of channels open for ion movement. Therefore, to accurately measure the movement of current through these channels in the plasma membrane, this pathway for movement has be lower resistance than the seal around the patch pipette contact with the cell membrane. A very high-resistance patch seal ensures that ionic currents flow across the cell membrane rather than escaping through the rim of the patch.
Subhead: Measurement of Single Channel Currents
Learning Objective: List three of the recording configurations that can be made with patch clamp methods and describe the advantages of each one.
Bloom’s Level: 3. Applying
Type: essay/short answer question
Title: Chapter 04 Question 55
55. Why do cell attached recordings of single channel openings look like square steps?
Feedback: The molecular transitions that occur between open and closed states are virtually instantaneous. At a given voltage across the membrane and a given concentration gradient for the ion the channel is permeable to, when the channel is open, there will be a fixed amount of current flux that will begin instantaneously. However, when the channel closes, this flux will stop instantaneously. This leads to the appearance of square steps in the measured single channel openings.
Subhead: Measurement of Single Channel Currents
Learning Objective: List three of the recording configurations that can be made with patch clamp methods and describe the advantages of each one.
Bloom’s Level: 2. Understanding
Type: essay/short answer question
Title: Chapter 04 Question 56
56. When using patch clamp recording, what is the difference between an “inside-out patch” and an outside-out patch”?
Feedback: An inside-out patch is formed when the experimenter starts by making a cell-attached patch and then pulls the patch off of the cell, rupturing the membrane on the outer surface of the pipette, creating a patch of membrane in which the intracellular surface of the membrane patch is oriented to face the outside of the pipette opening. In contrast, an outside-out patch is formed when the experimenter starts by making a cell-attached patch, then applies further suction to break that patch to create a whole-cell recording, and then pulls the patch pipette off of the cell, causing it to reseal creating a patch of membrane in which the extracellular surface of the membrane patch is oriented to face the outside of the pipette opening.
Subhead: Measurement of Single Channel Currents
Learning Objective: List three of the recording configurations that can be made with patch clamp methods and describe the advantages of each one.
Bloom’s Level: 2. Understanding
Type: essay/short answer question
Title: Chapter 04 Question 57
57. What is advantage of using a “perforated patch” recording technique instead of a traditional “whole-cell recording” technique?
Feedback: In traditional whole-cell recording, substances can move between the cell cytoplasm and the pipette. Because the volume of the solution in the patch pipette is much larger than the volume of the cytoplasm in the cell, important cytoplasmic components can be lost rapidly into the pipette solution. Such loss can be avoided by using a perforated patch, which uses a pore-forming antibiotic to only allow very small molecules (e.g. ions) to pass across the patch of membrane without the loss of intracellular macromolecules.
Subhead: Measurement of Single Channel Currents
Learning Objective: List three of the recording configurations that can be made with patch clamp methods and describe the advantages of each one.
Bloom’s Level: 5. Evaluating
Type: essay/short answer question
Title: Chapter 04 Question 58
58. Describe the methods for forming a whole-cell patch clamp recording.
Feedback: First, the experimenter touches the patch pipette to the outside of the cell and makes a seal to form a cell-attached patch. Then, by applying slight additional suction, the cell-attached patch is ruptured providing pipette access to the cell cytoplasm. In this condition, currents as ions pass through all the channels available to open from the entire cell (whole-cell recording).
Subhead: Measurement of Single Channel Currents
Learning Objective: List three of the recording configurations that can be made with patch clamp methods and describe the advantages of each one.
Bloom’s Level: 2. Understanding
Type: essay/short answer question
Title: Chapter 04 Question 59
59. The conductance of an ion channel can be measured is several ways. Explain the difference between “chord conductance” and “slope conductance,” and indicate when these two calculations might yield different values?
Feedback: The Chord conductance is the conductance calculated a one voltage assuming a linear relationship that passes through the equilibrium potential, while the slope conductance is calculated as the slope of the current–voltage relation (dI/dV) over a range of voltages that does not necessarily include the equilibrium potential. For ion channels that do not have a linear current-voltage relationship, these two calculations of conductance can yield different values.
Subhead: Measurement of Single Channel Currents
Learning Objective: Define channel conductance and name the two factors on which it depends.
Bloom’s Level: 2. Understanding
Type: essay/short answer question
Title: Chapter 04 Question 60
60. Can voltage-gated ion channels ever move an ion against its concentration gradient? If so, when does this occur?
Feedback: The direction of movement of the ions through an ion channel is governed by two forces: the concentration gradient across the membrane and the electrical membrane potential. Ions move in reaction to both forces. They move down their concentration gradient and are acted upon by the membrane potential dependent on their charge (e.g. a positive ion is repelled by a negative membrane potential to move out of the cell). If the force due to the membrane potential is large enough to be stronger than the force due to the concentration gradient, the net movement of ions can be against the concentration gradient.
Subhead: Measurement of Single Channel Currents
Learning Objective: Define channel conductance and name the two factors on which it depends.
Bloom’s Level: 5. Evaluating
Type: essay/short answer question
Title: Chapter 04 Question 61
61. Define and explain the equilibrium potential for an ion.
Feedback: The equilibrium potential for an ion is the electrical potential across the plasma membrane at which there is no net movement of that ion across the membrane when a channel for movement is open. This equilibrium is created when the force on the ion due to the electrical potential across the membrane and the force on the ion due to the concentration gradient across the membrane are equal and opposite. Under this condition, the flux of ions moving into and out of the cell due to these opposing forces are equal.
Subhead: Measurement of Single Channel Currents
Learning Objective: Explain what equilibrium potential is and what it depends on.
Bloom’s Level: 2. Understanding
Type: essay/short answer question
Title: Chapter 04 Question 62
62. Using the Nernst equation, what would you calculate the equilibrium potential for the sodium ion to be if the concentration of sodium outside was 130 mM, and the concentration of sodium in the cytoplasm was 12 mM?
Feedback: According to the Nernst equation:
ENa = 58 (log(concentration of the ion outside; in mM/concentration of the ion inside; in mM))
Therefore, ENa = 58 log 10.833
Which is equal to 58 1.035
Which is equal to 60.03 mV
Subhead: Measurement of Single Channel Currents
Learning Objective: Name the relationship given by the Nernst equation.
Bloom’s Level: 6. Creating