Final answer:
The sodium-potassium pump (Na+-K+ ATPase) is responsible for preventing the sodium concentration gradient from disappearing by actively transporting sodium out of the cell and potassium into the cell using ATP.
Step-by-step explanation:
The cellular process that prevents the sodium concentration gradient from disappearing is primarily the sodium-potassium pump (Na+-K+ ATPase). This pump continuously moves three sodium ions (Na+) out of the cell and two potassium ions (K+) into the cell against their concentration gradients, using ATP as the energy source. This active transport mechanism maintains the electrochemical gradient by ensuring high concentrations of sodium ions outside the cell and high concentrations of potassium ions inside the cell.
Moreover, the electrical gradient is maintained by negative proteins below the membrane that attract the sodium ion. The sodium-potassium pump, along with other factors like the opening of voltage-gated channels, helps to keep the cellular ionic environment balanced and supports functions such as nerve conduction.