That work is called . It directly uses energy (usually from ATP) to move molecules against their concentration gradient (from low to high). Think of it as pushing a boulder uphill.
During the electron transport chain, energy (though derived from redox reactions rather than direct ATP hydrolysis in this specific phase) is used to pump protons across the inner mitochondrial membrane, creating the gradient that eventually synthesizes ATP. Summary Table: Primary Active Transport Examples Primary Ion(s) Moved Key Location Na⁺/K⁺-ATPase 3 Na⁺ out / 2 K⁺ in Against gradient Most animal cells Ca²⁺-ATPase Out of cytosol Muscle cells, Plasma membrane H⁺/K⁺-ATPase H⁺ out / K⁺ in Into stomach Gastric parietal cells H⁺-ATPase Into organelle Lysosomes, Vacuoles Why Primary Active Transport Matters primary active transport examples
This pump pushes calcium out of the cell into the extracellular fluid. That work is called
Na+/K+cap N a raised to the positive power / cap K raised to the positive power During the electron transport chain, energy (though derived
Calcium levels inside the cytosol must be kept extremely low to prevent unwanted cell signaling. These pumps move Ca2+cap C a raised to the 2 plus power
Pumping Against the Tide: 3 Key Examples of Primary Active Transport
Primary active transport isn't just for the outer cell membrane; it’s crucial for internal organelles as well.