Question

Suppose you perform an alien autopsy on a creature from Area 51. You discover that instead of having a sodium/potassium pump, it has a sodium/magnesium pump. It works just the same, but pumps an ion of magnesium in place of each ion of potassium. Will the resting membrane potential (RMP) be more positive or more negative? Will the electrical gradient be larger or smaller? Explain your answer. (Hint: Magnesium has a charge of +2)       

Answer 1

We know that the distribution of ions across the cell membrane will make the resting membrane potential. Sodium distributed outside the cell membrane with charge +1 and pottassium inside membrane with +1 charge makes makes a negative membrane potential as the sodium ion concentration is more outside than the posttasium inside. So it means the change of the membrane is negative compared to outside the membrane. In case of potassium replaced by magnesium which has charge +2 the charge inside the membrane increases. As charge inside the membrane increases the the resting membrane potential moves to a positive value. So resting membrane potential would be more positive.

The electrical gradient will be smaller. We know that more sodium present outside and less pottassium inside made a huge difference in the gradient. As it is replaced by magnesium for an ion molecule the charge increased by +1 charge and become +2 for a molecule of ion of magnesium. So more charge is present inside. So the charge difference inside and outside the membrane decreases. This means the electrical gradient has become smaller.