gen-define-the-sodium-potassium-pump-and-give-one-short-worked-e-4a0e

Define the sodium-potassium pump and give one short worked example.

# Sodium-Potassium Pump ## Definition The **sodium-potassium pump** (Na⁺/K⁺-ATPase) is an active transport protein in cell membranes that maintains concentration gradients by pumping 3 sodium ions (Na⁺) OUT of the cell and 2 potassium ions (K⁺) INTO the cell against their concentration gradients, using energy from ATP hydrolysis. ## Key Features: - **Active transport** (requires energy) - Uses 1 ATP per cycle - Creates electrochemical gradients essential for nerve impulses, muscle contraction, and cell volume regulation --- ## Worked Example **Question:** A neuron uses its sodium-potassium pump continuously. If the pump completes 100 cycles, how many ions of each type are transported, and how many ATP molecules are consumed? **Solution:** Per cycle: - 3 Na⁺ pumped OUT - 2 K⁺ pumped IN - 1 ATP consumed For 100 cycles: - **Na⁺ transported out:** 3 × 100 = **300 Na⁺ ions** - **K⁺ transported in:** 2 × 100 = **200 K⁺ ions** - **ATP consumed:** 1 × 100 = **100 ATP molecules** **Result:** The pump maintains the cell's resting potential by removing 300 sodium ions, importing 200 potassium ions, and consuming 100 ATP molecules.