We often talk about cells "drinking" in nutrients or letting things diffuse in and out. But what happens when a cell needs something really bad, but that substance is already crowded outside? Or when it needs to push something out against the flow?
Also known as cotransport, this method doesn't use ATP directly. Instead, it hitches a ride on the energy created by primary transport. When an ion moves back down its gradient (created by primary transport), it "pulls" another molecule with it. active transport function
The most critical function of active transport is to create and sustain concentration differences of ions (such as sodium, potassium, calcium, and hydrogen) across the plasma membrane. For example, the sodium-potassium pump (Na⁺/K⁺ ATPase) actively pumps three sodium ions out of the cell and two potassium ions into the cell. This generates: We often talk about cells "drinking" in nutrients