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To write:
The description of three conformations of a voltage-gated Na+channel and indicate the membrane potential at which each of these conformations exist.
Introduction:
The Voltage-gated membrane channels consist of proteins that have many charged groups. The voltage-gated Na+ channel has 2 gates. They are- 1) Activationgate and 2) Inactivation gate. By opening and closing as a sliding door, the activation gate guards the channel's interior. The inactivation gate is an amino acid sequence with a ball-and-chain-like structure at the opening channel facing the ICF.This door is open when the ball hangs freely at the end of its chain and when the ball binds to the opening of the channel, thus blocking the opening. Both gates must be open to allow Na+ to go through the channel, and both gates must be closed to prevent passage.
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Human Physiology: From Cells to Systems (MindTap Course List)
- 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?)arrow_forwardOne of the important uses of the Nernst equation is in describing the flow of ions across plasma membranes. Ions move under the influence of two forces: the concentration gradient (given in electrical units by the Nernst equation) and the electrical gradient (given by the membrane voltage). This is summarized by Ohms law: Ix=Gx(VmEx) which describes the movement of ion x across the membrane. I is the current in amperes (A); G is the conductance, a measure of the permeability of x, in Siemens (S), which is I/V;Vm is the membrane voltage; and Ex is the equilibrium potential of ion x. Not only does this equation tell how large the current is, but it also tells what direction the current is flowing. By convention, a negative value of the current represents either a positive ion entering the cell or a negative ion leaving the cell. The opposite is true of a positive value of the current. a. Using the following information, calculate the magnitude of Na [ Na+ ]0=145mM,[ Na+ ]i=15mM,Gna+=1nS,Vm=70mV b. Is Na+ entering or leaving the cell? c. Is Na+ moving with or against the concentration gradient? Is it moving with or against the electrical gradient?arrow_forwardSeparately, 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.arrow_forward
- Compare the resting membrane potential of a neuron with the potassium and sodium equilibrium potentials. Explain how this comparison relates to the relative permeabilities of the resting plasma membrane to these two ions.arrow_forwardSeparately, 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 -40 mV (a, b, c, or d)? Upwards arrows means outward direction and downwards arrow means inward direction. The length of the arrow determines the magnitude.arrow_forwardCalculate the equilibrium membrane potentials to be expected across a membrane at 37 ∘C, with a NaCl concentration of 0.50M on the "right side" and 0.08 M on the "left side", given the following conditions. In each case, state which side is (+) and which is (−). (a)Membrane permeable only to Na+.arrow_forward
- Name the three phases of an action potential. Describe for each the underlying molecular basis and the ion involved. Why is the term voltage-gated channel applied to Na+ channels involved in the generation of an action potential?arrow_forwardThere are two types of gated ion channels. Name the 2 types and provide a description of how they workarrow_forwardWhat is the expected resting membrane potential (in mV) of a neuron that is typical in all ways except for possessing an intracellular potassium concentration of 94 mM and double the normal resting permeability to sodium?arrow_forward
- 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 0 mV?arrow_forwardWhat is the equilibrium membrane potential due to Na+ ions if the extracellular concentration of Na+ ions is 154 mM and the intracellular concentration of Na+ ions is 27 mM at 20 ∘C ? Please answer asap and in short and content should not be palgarised pleasearrow_forwardname the three ways in which an ion channel can be gated.arrow_forward
- Human Physiology: From Cells to Systems (MindTap ...BiologyISBN:9781285866932Author:Lauralee SherwoodPublisher:Cengage Learning