Question

E = 61/z *log(xo/xi)

You made an artificial cell that has a membrane completelyimpermeable to all ions. There are no ion channels or pumps

in the membrane. You fill the cell with 100 mM KCl, and place it inan extracellular solution containing 10 mM KCl.

(1) What is the electrical membrane potential measuredbetween the inside and the outside of the cell? Why?

You insert into the membrane of this cell ion channels that areselective only for K+ ions(note: these are the so-called

"leak" channels that are open all the time, regardless of membranepotential).

(2) What is the membrane potential now? Why?

You insert even more K+channels into the membrane, which makes it even more permeable toK+ ions.

(3) What is the membrane potentialnow?

You add 5 mM NaCl inside the cell, and 100 mM NaCl to theextracellular solution.

(4) Will the membrane potential change, and if so, will itbecome more negative or more positive? (Don