Final answer:
The hydrolysis of one ATP molecule releases 7.3 kcal/mol of energy, allowing three sodium ions to be actively transported across the cell membrane by the sodium-potassium pump, since it takes 2.1 kcal/mol of energy to move each sodium ion.
Step-by-step explanation:
The hydrolysis of one ATP molecule is a crucial process in cellular energy transfer, releasing 7.3 kcal/mol of energy. This energy release allows for the active transport of ions across the cell membrane, notably the sodium-potassium pump, which uses ATP to move sodium and potassium ions against their concentration gradients. Each cycle of the sodium-potassium pump transports three sodium ions out of the cell and two potassium ions into the cell.
To determine how many sodium ions could be moved by the hydrolysis of one ATP, we look at the energy requirement per ion, which is 2.1 kcal/mol. The sodium ions movement is an energy-dependent process, and by dividing the total energy available from one ATP molecule (7.3 kcal/mol) by the energy requirement to move one sodium ion (2.1 kcal/mol), we see that a maximum of approximately 3.48 sodium ions could be transported. However, since ions are transported in whole numbers, only three sodium ions are effectively moved across the membrane per ATP hydrolyzed.