question_answer

\[N{{a}^{+}}-{{K}^{+}}\]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 \[N{{a}^{+}}\]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 and \[3{{K}^{+}}\] are absorbed

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

Correct Answer: A

Solution :

Energy from ATP causeconfermational change in the solute carrier complex. From energy of one ATP, \[3N{{a}^{+}}\] 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 involving the \[N{{a}^{+}}\] - \[{{K}^{+}}\] - 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.