Final answer:
The electron transport chain in cellular respiration involves the transfer of electrons through a series of protein complexes, resulting in the production of water and the establishment of a proton gradient which facilitates ATP synthesis.
Step-by-step explanation:
When electrons are passed down the electron transport chain (ETC), they are transferred from the high-energy molecules NADH and FADH2 to a series of protein complexes located within the inner mitochondrial membrane. During this transfer, electrons move through these complexes and are finally accepted by oxygen, which combines with hydrogen ions to form water.
Through this process, energy is released, which is used to pump hydrogen ions (H+) across the inner membrane, creating an electrochemical gradient known as the proton gradient. This proton gradient is essential for chemiosmosis, where it drives the synthesis of ATP (adenosine triphosphate) by activating ATP synthase. Therefore, the main outcomes of the electron transport chain are the production of water and the creation of an energy gradient that is used for the generation of ATP, the cell's energy currency.