Question

$Na ^{+}- K ^{+}$pump is found in membranes of many cells, like nerve cells. It works against electro chemical gradient and involve an integral protein ATPase. For each molecule of ATP used:

• A. 3 ions of $Na ^{+}$are pumped out and two $K ^{+}$ are taken in
• B. 3 ions of $Na ^{+}$are taken in and $2 K ^{+}$are pumped out
• C. 2 ions of $Na ^{+}$are thrown out and $3 K ^{+}$are absorbed
• D. 3 ions of $K ^{+}$are absorbed and $3 Na ^{+}$are pumped out

Answer 1

Answer: (A)

Energy from ATP cause confermational change in the solute carrier complex. From energy of one ATP, $3 Na ^{+}$pumped outside and two $K ^{+}$ taken in. This process of expelling out $Na ^{+}$ions and drawing in $K ^{+}$ions against the concentration gradient and electrochemical gradient is called sodium-potassium exchange pump of the cell.

This pump operates by inovlving the $Na ^{+}- K ^{+}$-ATPase enzyme located in the cell membrane. Such electrogenic pump develops positive charge outside the membrane and a negative charge to cell's interior. This difference in charge on either side of the membrane of a resting neuron is the resting membrane potential.