Question

Consider an experimental setup with two compartments separated by a phospholipid bilayer membrane containing ion channels selectively permeable only to chloride ions. The left compartment (also called inside) contains 1 mM Cl- and the right compartment (also called outside) contains 100 mM Cl-. What will the electrical potential be when the system attains equilibrium

Answer 1

This question is incomplete, the complete question is;

Consider an experimental setup with two compartments separated by a phospholipid bilayer membrane containing ion channels selectively permeable only to chloride ions. The left compartment (also called inside) contains 1 mM Cl- and the right compartment (also called outside) contains 100 mM Cl-. What will the electrical potential be when the system attains equilibrium? [ assume body temperature; log 100 = 2, log 10 = 1, log 1 = 0, log 0.1 = -1, log 0.01 = -2]

Options;

a) -62 mV

b) -124 mV

c) +62 mV

d) 0 mV

e) +124 mV

Answer:

the electrical potential be when the system attains equilibrium is  –124mV

Option b) –124mV is the correct answer

Explanation:

Given the data in the question;

Two compartments are divided by lipid bilayer;

In inside compartment Cl- ion concentration- 1mM and out side of the cell concentration is 100mM

now we apply the Nernst equilibrium potential equation;

Chlorine ion valency is z = –1

So

$E_{eq}$ = 62/z × log(ion outside/ ion inside) [for Cl‐ ions]

$E_{eq}$ = (62 / –1) x log(  100 / 1 )

 $E_{eq}$ = -62 x 2 =

$E_{eq}$  = –124mV

Therefore, the electrical potential be when the system attains equilibrium is  –124mV

Option b) –124mV is the correct answer