Question

In what ratio does the Na\(^+\)/K\(^+\) pump transport sodium and potassium ions?

• A. \(2\ \mathrm{Na^+}\) out : \(2\ \mathrm{K^+}\) in
• B. \(3\ \mathrm{Na^+}\) out : \(2\ \mathrm{K^+}\) in
• C. \(2\ \mathrm{Na^+}\) in : \(3\ \mathrm{K^+}\) out
• D. \(1\ \mathrm{Na^+}\) out : \(1\ \mathrm{K^+}\) in

Hint:

The Na\(^+\)/K\(^+\)-ATPase uses \[ \boxed{1\ \mathrm{ATP}} \] to transport \[ \boxed{ 3\ \mathrm{Na^+}\ \text{out} \quad\text{and}\quad 2\ \mathrm{K^+}\ \text{in}. } \] This pump is electrogenic because more positive charges leave the cell than enter.

Answer 1

The Correct Option is B

Step 1: Recall the function of the Na\(^+\)/K\(^+\)-ATPase. The sodium-potassium pump is an ATP-driven membrane protein that maintains ionic gradients across the plasma membrane.

Step 2: State the transport ratio. For every ATP molecule hydrolyzed, \[ \boxed{ 3\ \mathrm{Na^+} \text{ are pumped out of the cell} } \] and \[ \boxed{ 2\ \mathrm{K^+} \text{ are pumped into the cell.} } \] Thus, the transport ratio is \[ \boxed{ 3\ \mathrm{Na^+}\text{ out} : 2\ \mathrm{K^+}\text{ in}. } \] Therefore, \[ \boxed{(B)} \] is the correct answer.