One of the following is TRUE? A. The transport of Na+ across cell membranes depends solely on concentration gradient B. The transport of sucrose across cell membranes depends solely on concentration gradient C. The transport of K+ across cell membranes depends solely on concentration gradient D. The transport of Ca2+ across cell membranes depends solely on concentration gradient E. A & C

One of the following is TRUE? A. The transport of Na+ across cell membranes depends solely on concentration gradient B. The transport of sucrose across cell membranes depends solely on concentration gradient C. The transport of K+ across cell membranes depends solely on concentration gradient D. The transport of Ca2+ across cell membranes depends solely on concentration gradient E. A & C

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

9th Edition

ISBN:9781285866932

Author:Lauralee Sherwood

Publisher:Lauralee Sherwood

Chapter3: The Plasma Membrane And Membrane Potential

Section: Chapter Questions

Problem 2TAHL: Assume that a membrane permeable to Na+ but not to Cl- separates two solutions. The concentration of...

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Ion transporters are “linked” together—not physi-cally, but as a consequence of their actions. For example,cells can raise their intracellular pH, when it becomes tooacidic, by exchanging external Na+ for internal H+, usinga Na+–H+ antiporter. The change in internal Na+ is thenredressed using the Na+-K+ pump.A. Can these two transporters, operating together,normalize both the H+ and the Na+ concentrations insidethe cell?B. Does the linked action of these two pumps causeimbalances in either the K+ concentration or the mem-brane potential? Why or why not?
Inhibition of the Na,K-ATPase might reasonably result in which of the following: a.) gradual cellular accumulation of K+ b.) gradual decrease in cytoplasmic Na+ c.) cell shrinkage d.) hyperpolarization of the membrane potential e.) reduced activity of many secondary active transporters
Na+ moves from high to low concentration, across the plasma membrane, through a protein channel that is permenantly open. Which statement is true about this process? a. It does not require ATP b. It is a form of active transport c. Movement is against the concentration gradient of Na+ d. The channel probably allows many different molecules and ions to cross
Given two cells that are identical in all ways except that extracellular concentration of Na+ ions is grater for cell A differ from that that in cell B if stimuli of identical strength were applied to each
During neuronal signaling, a change in membrane potential will cause sodium channelsto open and let Na+ ions diffuse down their concentration gradient into the cell. Whichof the following helps establish the concentration gradient necessary for this process tooccur?
The energy source for movements of Na* and K* during an action potential is a. the Na*/K* ATPase b. the thermal energy in the cell membrane c. the concentration gradients for the ions d. determined by the lipids of the cell membrane e. the negative charge of the extracellular fluid relative to the cytosol
Given these three statement- two of which are truths and one is a lie. Which of the following statements is a lie? Select one: a. Unless a channel of a carrier protein is open, cations remain outside. b. When we experimentally induce a positive charge in the inside of the cell, cations will be forced out. c. Equal concentrations are achieved in the ions involved in the electrochemical gradient. Given these three statements - two of which are truths and one is a lie. Which of the following statements is a lie? Select one: a.The primary active transport prepares the conditions of the membrane gradient by making the extracellular membrane have a less negative charge in the concentration gradient than the intracellular membrane. b. The primary active transport uses ATP while secondary transport helps replenish ATP. c. Both primary and secondary transport moves solutes against their concentration gradients.
Assume that a membrane permeable to Na+ but not to Cl- separates two solutions. The concentration of sodium chloride on side 1 is higher than on side 2. Which of the following ionic movements would occur? a. Na+ would move until its concentration gradient is dissipated (until the concentration of Na+ on side 2 is the same as the concentration of Na+ on side 1). b. Cl- would move down its concentration gradient from side 1 to side 2. c. A membrane potential, negative on side 1, would develop. d. A membrane potential, positive on side 1, would develop. e. None of the preceding is correct.
One 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?
Describe the contribution of each of the following to establishing and maintaining membrane potential: (a) the Na+K+ pump, (b) passive movement of K+ across the membrane, (c) passive movement of Na+ across the membrane, and (d) the large intracellular anions.
a. Molecule X is a soluble protein that is secreted in response to extracellular signal Y. Which sorting signal must molecule X have? b. Why is the sorting signal mentioned above important for the sorting of molecule X? Explain c. Extracellular signal Y is a soluble cytosolic protein. Taking into consideration the composition and property of plasma membrane, discuss how the cell receives information from extracellular signal Y and relays the information through the plasma membrane?
Very briefly, explain how increased cytoplasmic IP3 levels can then increase cytoplasmic calcium (Ca2+) levels.