Final answer:
The sodium-potassium pump moves three Na+ ions out for every two K+ ions in, creating a net negative charge inside the cell and maintaining the electrochemical gradient necessary for various cellular functions.
Step-by-step explanation:
The sodium-potassium pump maintains a specific ratio of ion movement across the cell membrane: three sodium ions (Na+) are transported out of the cell for every two potassium ions (K+) brought in. This movement is against their respective concentration gradients and requires energy in the form of ATP. The 3:2 exchange ratio is crucial because it results in a net loss of one positive charge from the cell, contributing to a negative charge inside the cell and maintaining the necessary electrochemical gradient for cellular functions like nerve impulse transmission and muscle contraction.
The pump is an example of an electrogenic pump, which not only helps in the transport of ions but also generates an electrical imbalance across the cell membrane. This imbalance is referred to as the membrane potential, vital for the functioning of cells, especially in transmitting nerve impulses and muscle contractions.