The role of the sodium-potassium pump in cellular function is to maintain electrochemical gradients across the cell membrane. This active transport mechanism moves sodium ions out of the cell and potassium ions into the cell, against their respective concentration gradients. By utilizing ATP as energy, the sodium-potassium pump plays a critical role in regulating cell volume, creating a resting membrane potential necessary for nerve impulses, and facilitating various cellular processes, including nutrient uptake and waste removal.