Based on the information provided in Question #2, answer each of the following q

Question

Based on the information provided in Question #2, answer each of the following questions; clearly label each answer with the indicated letter. Assume that the typical eukaryotic cell is at rest and Vr = -80 mV.

(a) Would the chemical driving force acting on X2- favor the movement of X2-INTO or OUT OF the cell?  Carefully explain your answer.

(b) Would the electrical driving force acting on X2- favor the movement of X2-INTO or OUT OF the cell?  Carefully explain your answer.

(c) If our plasma membranes were made suddenly permeable to X2-, in which direction would there be net movement of X2-ions? Assume the cell was at rest prior to this increased permeability.  Carefully explain your answer.

(d) The net movement of X2- ions, which you describe in your answer to Part (C), would generate a __________ (depolarization or hyperpolarization).  Briefly explain your answer.

(e) Following up your answer to Part (C): at what point would there no longer be any further net movement of X2-ions?  Briefly explain your answer.

Explanation / Answer

a) The concentration of anion X2 is right times higher inside the cell than outside. So, the chemical driving force will act on the anion X2 to favor it's movement out of the cell.

b) The resting membrane potential of the cell is -80 mV. This shows that the inside of the cell is negative when compared to the outside. Therefore, the electrical driving force acting on the anion X2 will favor the movement of X2 out of the cell.

c) If the plasma membrane is made permeable to X2, it will move along its concentration gradient from inside of the cell to outside.

d) Since, there is a loss of negative ions inside the cell, the resting membrane potential increases towards the positive side resulting in depolarisation.

e) When the concentration of X2 becomes equal on both the sides of plasma membrane (intracellular concentration of the ion equals the extracellular concentration), there will no longer be any further movement of X2- ions.

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