. The average human generates approximately his or her weight in ATP every day. A resting person uses about 25% of this in ion transport- mostly via the Na+-K* ATPase. About how many grams of Na+ and K* will a sedentary 70-kg person pump across membranes in a day?

. The average human generates approximately his or her weight in ATP every day. A resting person uses about 25% of this in ion transport- mostly via the Na+-K* ATPase. About how many grams of Na+ and K* will a sedentary 70-kg person pump across membranes in a day?

Biology: The Dynamic Science (MindTap Course List)

4th Edition

ISBN:9781305389892

Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Publisher:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Chapter5: Membranes And Transport

Section: Chapter Questions

Problem 4TYK: A characteristic of carrier molecules in a primary active transport pump is that: a. they cannot...

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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?
Figure 6.14 The hydrolysis of one ATP molecule releases 7.3 kcal/mol of energy (?G = -7.3 kcal/mol of energy). If it takes 2.1 kcal/mol of energy to move one Na+ across the membrane (?G = +2.1 kcal/mol of energy), how many sodium ions could be moved by the hydrolysis of one ATP molecule?
The rate at which the Na+K+ pump operates is not constant but is controlled by a combined effect of changes in ICF Na+ concentration and ECF K+ concentration. Do you think the changes in both ICF Na+ and ECF K+ concentration following a series of action potentials in a neuron would accelerate, slow down, or have no effect on the Na+K+ pumps in this cell?
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.
Using the Goldman-Hodgkin-Katz equation, determine what happens to the resting membrane potential if the ECF K+ concentration doubles to 10 mM.
List the means of unassisted membrane transport.
Body fluids of a marine bony fish have a solute concentration that is _____ its surroundings. a. higher than b. lower than c. equal to
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.
Calculate the number of cells in the body of an average 68-kg (150-lb) adult. (This will only be accurate to about 1 part in 10 but should give you an idea how scientists estimate this commonly quoted number.) Assume all cells are spheres 20 m in diameter. The volume of a sphere can be determined by the equation v=4/33. (Hint: We know that about two thirds of the water in the body is intracellular and the density of cells is nearly 1 g/mL. The proportion of the mass made up of water is about 60%.)
Test Your Understanding 7.In cotransport (indirect active transport) (a) a uniporter moves a solute across a membrane against its concentration gradient (b) the move of one solute down its concentration gradient provides energy for transport of some other solute up its concentration gradient (c) a channel protein moves ions by facilitated diffusion (d) osmosis powers the movement of ions against their concentration gradient (e) sodium is directly transported in one direction, and potassium is indirectly transported in the same direction
Jogging is considered aerobic exercise because the cardiovascular system (heart and blood vessels) can adjust to supply the oxygen needs of working cells. In contrast, sprinting the 100-meter dash might be called anaerobic (lacking oxygen) exercise, and golf nonaerobic exercise. Explain these last two observations.
Which of the following is not produced by an animal muscle cell operating under anaerobic conditions? a. heat d. ATP b. pyruvate e. lactate c. PGAL f. oxygen