Final answer:
The sodium-potassium pump is a specialized protein that uses energy to move sodium ions out and potassium ions into a cell, maintaining ion gradients and electrical charge needed for cellular functions.
Step-by-step explanation:
The specialized membrane proteins that actively transport sodium and potassium ions across the plasma membrane are known as the sodium-potassium pump. This type of transport is active because it requires energy in the form of ATP to move the ions against their concentration gradient, which involves pumping sodium ions out of the cell and potassium ions into the cell. The pump works by using carrier proteins that bind with the specific ions and, while undergoing a change in shape, transport the ions across the membrane. The sodium-potassium pump is crucial for maintaining the necessary concentration gradients and electrical charge across the cellular membrane, which are essential for various cellular processes such as nerve signal transmission and muscle contraction.