Question

A single Na /K ATPase pump is present in the plasma membrane of an artificial cell with an initial cellular environment of 1000 molecules of Na and 1000 molecules of ATP inside the cell, 1000 molecules of K outside the cell, and a net charge differential across the plasma membrane of 0. Assuming the only changes in the cellular environment are a result of the pump's actions, what would be the number of Na , K and ATP molecules inside the cell after 100 cycles of the pump and what would be the net charge differential (inside - outside) across the plasma membrane?

Answer 1

Answer:

The correct answer is: there will be 700 Na+ molecules, 200 K+ molecules, 900 ATP molecules, and a net charge differential of -200.

Explanation:

Inside the cell, there's 1000 molecules of Na+ and 1000 molecules of ATP.

Outside the cell, there's 1000 molecules of K+.

The Na+/K+ ATPase expels 3 molecules of Na+ and enters 2 molecules of K+ with every pump.

If there's only one Na/K ATPase and there are not other changes in the cellular environment, and the Na/K ATPase pumps 100 times, we can assume that 300 molecules of Na+ will exit the cell, and 200 molecules of K+ will enter the cell. Every pump costs 1 ATP molecule, so there will be 100 ATP molecules used.

"what would be the number of Na , K and ATP molecules inside the cell after 100 cycles of the pump and what would be the net charge differential (inside - outside) across the plasma membrane?"

Na+ inside the cell: 1000 - 300 = 700 Na+ molecules.

K+ inside the cell: 200 K+ molecules.

ATP inside the cell: 1000 - 100 = 900 ATP molecules.

Net charge differential: -200

Answer 2

Answer / Explanation:

To properly understand this question, let us first try to understand what an Na+ K+ pump is:

The Na+ K+ pump is an electro-genic transmembrane ATPase. Situated in the outer plasma membrane of the cells; on the cytosolic side.

We need to also know that the plasma membrane is a lipid bilayer arranged asymmetrically and contains cholesterol, phospholipids, glycolipids, sphingolipid, and proteins within the membrane. Part of the function of the Na+K+ -ATPase pump is to helps maintain osmotic equilibrium and membrane potential in cells.

With the understanding of the above, if we go further to solving the question, we have:

700 Na+; 200 K+; 900 ATP and -200 charge differential (inside - outside).

So for further explanation,

We can say that:

For the Inside cells, there are 1000 molecules of Na+ and 1000 molecules of ATP.

For the Outside cells, there's 1000 molecules of K+.

The Na+/K+ ATPase dismisses 3 molecules of Na+ and enters 2 molecules of K+ with every pump.

Therefore, If there's only one Na/K ATPase and there is no changes in the cellular environment,

Hence, the Na/K ATPase pumps 100 times.

So we can suggest that 300 molecules of Na+ will leave the cell, and 200 molecules of K+ will enter the cell.

Every pump costs 1 ATP molecule, so there will be 100 ATP molecules used.

Therefore, we can conclude that:

700 Na+; 200 K+; 900 ATP and -200 charge differential (inside - outside) which represent or equates to the answer we are looking for.