Question

In the Na/K pump, how many molecules of sodium are transported and how many molecules of potassium are transported in each cycle?

A) 1 sodium, 2 potassium
B) 2 sodium, 1 potassium
C) 3 sodium, 1 potassium
D) 1 sodium, 3 potassium

Answer 1

In each cycle of the Na/K pump, three sodium ions are expelled from the cell, and two potassium ions are brought in, with the activity powered by ATP hydrolysis.

Step-by-step explanation:

In the Na/K pump, three sodium ions (Na+) are transported out of the cell, while two potassium ions (K+) are transported into the cell in each cycle. This active transport mechanism utilizes energy derived from ATP to move the ions against their concentration gradients. Specifically, the steps involved are:

1. Three sodium ions bind to the protein inside the cell.
2. ATP is hydrolyzed, and the carrier protein is phosphorylated.
3. The carrier changes shape and releases the three sodium ions outside the cell.
4. Two potassium ions from outside the cell bind to the carrier protein.
5. The shape change allows the two potassium ions to be transported into the cell.

These steps repeat, maintaining the essential electrochemical gradient and ion balance required for various cellular processes.