Ion channels, such as the K+ channel, can have open and closed forms that respond to membrane potential. In addition, an amino-terminal domain, called the inactivation domain or inactivation gate, can block the channel. This is called the ball and chain model of channel inactivation. Identify the statements that correctly describe the ball and chain model. The inactivation gate can only inactivate a channel that has closed in response to depolarization. A shorter tether or chain peptide strand attached to the inactivation domain would increase the time required to inactivate the K+ channel. A mutation causing the loss of the inactivation gate in K+ channels could result in a membrane that undergoes repolarization more slowly. After depolarization and channel opening, the inactivation gate soon occludes the open channel.

Ion channels, such as the K+ channel, can have open and closed forms that respond to membrane potential. In addition, an amino-terminal domain, called the inactivation domain or inactivation gate, can block the channel. This is called the ball and chain model of channel inactivation. Identify the statements that correctly describe the ball and chain model. The inactivation gate can only inactivate a channel that has closed in response to depolarization. A shorter tether or chain peptide strand attached to the inactivation domain would increase the time required to inactivate the K+ channel. A mutation causing the loss of the inactivation gate in K+ channels could result in a membrane that undergoes repolarization more slowly. After depolarization and channel opening, the inactivation gate soon occludes the open channel.

Human Physiology: From Cells to Systems (MindTap Course List)

9th Edition

ISBN:9781285866932

Author:Lauralee Sherwood

Publisher:Lauralee Sherwood

Chapter4: Principles Of Neural And Hormonal Communication

Section: Chapter Questions

Problem 1RE: Conformational changes in channel proteins brought about by voltage changes are responsible for...

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Conformational changes in channel proteins brought about by voltage changes are responsible for opening and closing Na+ and K+ gates during the generation of an action potential. (True or false?)
Which of the following statements best describes the features of voltage-gated K+ channels? They consist of 4 subunits, are activated at the same time as voltage-gated Na+ channels, but do not inactivate. They consist of 4 subunits, are activated by depolarisation and close slowly during the refractory period. They have 24 membrane spanning alpha helices, 4 of which have positively charged amino acids which promote a conformational change in the channel following depolarisation. They consist of 4 subunits and are open at rest which causes the resting membrane potential to be close to the K+ equilibrium potential.
Separately, draw a table using arrows to depict the appropriate magnitude and direction of the forces and ion fluxes at different membrane potentials for a ligand-gated channel that is equally permeable to both ion X+ and ion Y+. The equilibrium potential for ion X+ is -60 mV, and the equilibrium potential for ion Y+ is -20 mV. Which item (a, b, c, or d) best represents the forces and fluxes for a membrane potential of +20 mV? Upwards arrows means outward direction and downwards arrow means inward direction. The length of the arrow determines the magnitude.
Separately, draw a table using arrows to depict the appropriate magnitude and direction of the forces and ion fluxes at different membrane potentials for a ligand-gated channel that is equally permeable to both ion X+ and ion Y+. The equilibrium potential for ion X+ is -60 mV, and the equilibrium potential for ion Y+ is -20 mV. Which item best represents the forces and fluxes for a membrane potential of -60 mV? Pick one of the four tables in the included image please for your answer.
Separately, draw a table using arrows to depict the appropriate magnitude and direction of the forces and ion fluxes at different membrane potentials for a ligand-gated channel that is equally permeable to both ion X+ and ion Y+. The equilibrium potential for ion X+ is -60 mV, and the equilibrium potential for ion Y+ is -20 mV. Which item best represents the forces and fluxes for a membrane potential of +20 mV?
Draw the current changes caused by a single voltage gated Potassium channel when the membrane is voltage-clamped at different voltage values (see below). Assume an equilibrium potential for potassium of -70mV and don't worry about exact values for the currents (approximations are fine). Label the axes on the traces and describe how the dynamics of individual voltage gated potassium channels come together to form the macroscopic K+ currents during depolarization. . a. @Resting Membrane Potential = -70 mV b. @Voltage Step = -20 mV c. @Voltage Step = +50mV
Which of the following statements about voltage gated channels is true? Voltage-gated sodium channels open at a higher (more positive) membrane potential than do potassium-gated channels Voltage-gated sodium channels open at a lower (more negative) membrane potential than do potassium-gated channels Sodium- and postassium-gated channels open at about the same membrane potential, but they have different effects because there are different numbers of the two kinds of channels in neuron cell membranes
The top panel (a) of this figure shows the graded potential change (far right, upper, electrical trace) that results from ligand binding to the ligand gated Na+ channel. The bottom panel of this figure (b) shows a graded potential change (far right, lower, electrical trace) that results from ligand binding to a ligand gated Cl- channel. From this trace you know (Vm = -70 mV) 1. ECl- is -70 mV 2. ECl- is more negative than -70 mV (i.e., -80 mV) 3. ECl- is more positive than -70 mV (i.e., -60 mV)
Buckeyium is a medication that binds to the NMDA receptor at the orthosteric binding site (were glutamate would normally bind). Assume glycine is already bonded and magnesium isn't inhibiting the NMDAR ion channel. Buckeyium would be regarded a poison if the channel did not open as a consequence of its binding.
The rapid upstroke of a SA nodal cell action potential is due to the opening of voltage-gated Na+ channels. answer should clearly state whether or not the statement is correct and then concisely explain why. the answer should be 3-5 sentences and address all of the points in the statement. Here is an example: Both transmembrane carrier proteins and transmembrane channel proteins can mediate active transport of a hydrophilic solute through a cell plasma membrane. This statement is incorrect. Movement of a solute through a channel protein is always passive, whereas carrier-mediated transmembrane transport can be either passive or active. A transmembrane channel protein creates a pore through the membrane allowing for simple diffusion of a hydrophilic solute down a concentration gradient through the membrane. In contrast, transmembrane carrier protein interacts with and ‘escorts’ a hydrophilic solute through the membrane and is capable of transporting a solute against a concentration…
Batrachotoxin (BTX) is a steroidal alkaloid from the skin of Phyllobates terribilis , a poisonous Colombian frog (the source of the poison used on blowgun darts). In the presence of BTX, Na+ channels in an excised patch stay persistently open when the membrane is depolarized. They close when the membrane is repolarized . Which transition is blocked by BTX?
The drug Buckeyium binds to the NMDA receptor at the orthosteric binding site (were glutamate would normally bind). Assume that glycine is already bound, and that magnesium is not blocking the NMDAR ion channel. If the channel does not open as a result of Buckeyium binding than Buckeyium would be considered a