Primary And Secondary Active Transport • Authentic & Reliable

For a cell to survive, it can’t just go with the flow. While passive transport (like diffusion) allows substances to move from high to low concentration for "free," cells often need to pull in nutrients or pump out waste against the natural gradient. This uphill battle is known as .

Example: The in the gut uses the inward flow of Sodium to "pull" Glucose into the cell, even when glucose levels are already high inside. primary and secondary active transport

| Feature | | Antiport (Countertransport) | | :--- | :--- | :--- | | Direction | Both solutes move in the same direction across the membrane. | Solutes move in opposite directions. | | Driving Ion | Usually Na⁺ moving down its gradient (into the cell). | Na⁺ or H⁺ moving down its gradient (into the cell) drives another solute out. | | Example | SGLT (Sodium-Glucose Linked Transporter) | Sodium-Calcium Exchanger (NCX) | For a cell to survive, it can’t just go with the flow