question_answer

\[N{{a}^{+}}-~{{K}^{\text{+}}}\] 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 \[N{{a}^{+}}\] are pumped out and two \[{{K}^{+}}\] are taken in

B) 3 ions of \[N{{a}^{+}}\] are taken in and \[2{{K}^{+}}\] are pumped out

C) 2 ions of \[N{{a}^{+}}\] are thrown out \[3{{K}^{+}}\] are absorbed

D) 3 ions of \[{{K}^{+}}\] are absorbed and \[3N{{a}^{+}}\] are pumped out

Correct Answer: A

Solution :

Energy from ATP cause conformational change in the solute carrier complex. From energy of one ATP, 3 \[N{{a}^{+}}\] are pumped outside and two \[{{K}^{+}}\] are taken in. This process of expelling out \[N{{a}^{+}}\] 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 involving the \[N{{a}^{+}}-{{K}^{+}}\,\,-\] ATPase enzyme located in the cell membrane. Such electrogenic pump develops positive charge outside the membrane and 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.