Question

The first step of the Na⁺/K⁺ pump's activity involves the binding of which of the following?

a) ATP.
b) Sodium ions.
c) Potassium ions.
d) Chloride ions.

Answer 1

The first step of the Na⁺/K⁺ pump's activity involves the binding of sodium ions, which triggers the subsequent steps of the pumping cycle that maintains the cell's electrochemical gradient.

Step-by-step explanation:

The first step of the Na⁺/K⁺ pump's activity involves the binding of sodium ions (Na⁺). This step is crucial for the pump to initiate its function of maintaining the electrochemical gradient across the cell membrane. Here are the basic stages of the pump's activity:

1. Three sodium ions bind to the protein carrier within the intracellular space.
2. ATP is hydrolyzed by the protein carrier, and a phosphate group attaches to the carrier, releasing energy.
3. The carrier changes its shape, opens outward, and releases the bound sodium ions outside the cell.
4. Two potassium ions (K⁺) then bind to the protein carrier.
5. The phosphate group is released, leading to a conformational change that translocates the potassium ions into the cell.
6. The pump returns to its original conformation, ready to start the cycle again.

The binding sites for Na⁺, K⁺, and ATP on the Na⁺/K⁺ pump suggest that these ions and the energy molecule play specific roles at certain stages during the pump's cycle. In summary, sodium ions are the first to bind to the Na⁺/K⁺ pump, initiating the ion transport process.