Question

The Na+/ K+ pump transports in which directions and what amounts per molecule of ATP

hydrolyzed?
A) 3 sodium ions in and 3 potassium ions out per molecule of ATP hydrolyzed
B) 3 sodium ions out and 2 potassium ions in per molecule of ATP hydrolyzed
C) They are transported in a 3:2:1 ratio in opposite directions.
D) They are transported in a 1:1 ratio in opposite directions per molecule of ATP hydrolyzed.
E) They are transported in a 3:2:2 ratio.

Answer 1

The Na+/K+ pump transports 3 sodium ions out of the cell and 2 potassium ions into the cell per molecule of ATP hydrolyzed, using energy from the hydrolysis of ATP to maintain the necessary electrochemical gradients across the cell membrane.

Step-by-step explanation:

The Na+/K+ pump transports ions in specific directions and amounts for each molecule of ATP hydrolyzed. The correct transport mechanism involves the pump moving 3 sodium ions out of the cell and 2 potassium ions into the cell per molecule of ATP hydrolyzed. This process is an example of active transport, which is essential for maintaining the electrochemical gradients across the cell membrane that are critical for nerve impulse transmission and muscle contraction.

The steps involved are as follows:

1. Three sodium ions bind to the sodium-potassium pump within the cell.
2. ATP is hydrolyzed, transferring a phosphate to the pump, causing it to change shape.
3. This shape change results in the three sodium ions being released outside the cell.
4. Subsequently, two potassium ions from outside the cell bind to the pump.
5. The pump then changes shape again, allowing for the transport of the two potassium ions into the cell.
6. The cycle can then repeat with a new ATP molecule.