So the next time you feel tired trying to get a task done, remember your cells: They are constantly swimming upstream, carrying heavy bags, and working against the odds—all to keep you alive.
Think of a hydroelectric dam. The water stored up high (created by primary transport) has potential energy. When you let the water flow down, you can use that flow to power something else (like a turbine). 3 types of active transport
In secondary transport, a molecule (like sodium) naturally wants to flow back into the cell (down its gradient). A co-transporter protein lets that sodium ion fall back in, but only if it brings a "passenger" molecule (like glucose) along for the ride—even if the glucose is moving against its own gradient. So the next time you feel tired trying
