Sodium-Potassium Pump (Na+-K+ pump) • Also known as the Na+-K+ ATPase because it is an enzyme that hydrolyzes ATP • Binds 3 Na+ on the cytoplasmic side (or ICF) of the cell and pumps them out to the ECF • Simultaneously, binds 2 K+ from the ECF and pumps them into the ICF • Each time it does this it uses 1 ATP • Net exchange = 3 Na+ for 2 K+ • Physiological results: 1. Keeps the concentration of K+ > Na+ inside the cell 2. Keeps the concentration Na+ > K+ outside of the cell 3. Net charge on plasma membrane = -1 on the inside; +1 on the outside RESTING MEMBRANE POTENTIAL • Describe the four functions of the Na+-K+ pump: 1. Secondary active transport 2. Regulation of cell volume 3. Maintenance of the membrane potential 4. Heat production
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Secondary active transport: The Na+-K+ pump uses the energy from ATP hydrolysis to actively transport Na+ and K+ ions across the cell membrane against their concentration gradients. This process is known as secondary active transport because it relies on the Show more…
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A sodium-potassium pump has a transmembrane transport protein that uses energy to transport Na+ and K+ ions through the cell and maintain a high concentration of K+ inside the cell. The continuous active transport can be broken down into four steps. Put the four steps of the sodium-potassium pump into the correct order. ATP and 3 Na+ bind to the cytoplasmic surface of the Na+/K+ pump. ATP is hydrolyzed; Na+ is released into the extracellular fluid. 2 K+ bind to the extracellular surface of the Na+/K+ pump; PO4- (from ATP hydrolysis) is released into the cytoplasm. K+ is released into the cytoplasm.
Bryan V.
How does the sodium-potassium pump contribute to the net negative charge of the interior of the cell? a. The sodium-potassium pump forces out three (positive) $\mathrm{Na}^{+}$ ions for every two (positive) $\mathrm{K}^{+}$ ions it pumps in, thus the cell loses a net positive charge of one at every cycle of the pump. b. The sodium-potassium pump expels three ions $\mathrm{K}^{+}$ for every two $\mathrm{Na}^{+}$ inside the cells, creating a net positive charge outside the cell and a net negative charge inside the cell. c. The sodium-potassium pump helps the development of negative charge inside the cell by making the membrane more permeable to negatively charged proteins. d. The sodium-potassium pump helps in the development of negative charge inside the cell by making the membrane impermeable to positively charged ions.
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