The Mitochondrial Electron Transport Chain (ETC) is a series of protein complexes located in the inner membrane of mitochondria. It plays a crucial role in cellular respiration by transferring electrons derived from nutrients. As electrons move through the chain, they release energy, which is used to pump protons across the membrane, creating a proton gradient. This gradient drives the synthesis of adenosine triphosphate (ATP) through a process called oxidative phosphorylation. The final electron acceptor in the chain is oxygen, which combines with electrons and protons to form water. This process is essential for producing the energy needed for various cellular functions.