Question

special single cell organism that lives in a natural mineral water spring has permeabilities of 0.09, 1.00 and 0.04 for the Cl^-, K⁺ and Na⁺, respectively, and the following concentrations

            [Cl^-]_i = 178                  [Cl^-]_o = 0.47
            [K⁺]_i = 135                  [K⁺]_o = 83
            [Na⁺]_i = 0.05               [Na⁺]_o = 118

To maintain the chloride gradient, this cell has a special chloride pump.

Which direction does the pump have to move chloride in order to maintain the status?

Answer 1

The pump must pump chloride ion from outside the cell to the inside to maintain the chloride ion gradient. This can be achieved by active transport by utilising ATP the chloride ions can be pumped from low to high concentration. Or it can also use co transport. In which the Sodium ions can be moved twords the gradient which is a downhill reaction and simultaneously the chloride ions can be moved against the concentration gradient which is an uphill reaction.