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
