Final answer:
The electron transport chain (ETC) in cells transports electrons down the inner mitochondrial membrane or plasma membrane of prokaryotes. This movement creates a gradient that is used to generate ATP through chemiosmosis.
Step-by-step explanation:
The electron transport chain (ETC) is a series of redox reactions that occur in the inner membrane of mitochondria or the plasma membrane of prokaryotes. The ETC consists of protein complexes and electron carriers that transport electrons from higher to lower energy states. As the electrons move down the ETC, hydrogen ions (H*) are pumped across the membrane, creating a gradient. This gradient is then used to generate ATP through the process of chemiosmosis. ATP synthase, a membrane-bound enzyme complex, facilitates the movement of hydrogen ions back across the membrane, driving the synthesis of ATP.