In symport, both the "driving" ion and the "passenger" molecule move in the same direction. Usually Sodium (Na+) or Hydrogen (H+).
Life at the cellular level is a constant battle against entropy. To maintain order, orchestrate signaling, and acquire essential nutrients, cells must move molecules across their selectively permeable plasma membranes. While some molecules drift passively down their concentration gradients, many others—such as amino acids, sugars, and ions—must be moved against their electrochemical gradient, a process requiring energy. Primary active transport, exemplified by the sodium-potassium pump, directly hydrolyzes ATP to fuel this movement. However, cells possess an equally vital but more subtle mechanism: . This process is best defined as the coupled movement of a solute against its concentration gradient, driven not by direct ATP hydrolysis, but by the potential energy stored in the electrochemical gradient of a second solute—typically sodium ions (Na⁺) in animal cells or protons (H⁺) in bacteria and plants. what is secondary active transport
There are two main ways this process occurs, categorized by the direction in which the molecules move. 1. Symport (Cotransport) In symport, both the "driving" ion and the