Hengitysketjun

Hengitysketjun, also known as the respiratory chain or electron transport chain, is a series of protein complexes and molecules found in the inner mitochondrial membrane. It plays a crucial role in cellular respiration, the process by which cells generate energy in the form of ATP (adenosine triphosphate). The respiratory chain is responsible for the transfer of electrons from electron donors, such as NADH (nicotinamide adenine dinucleotide) and FADH2 (flavin adenine dinucleotide), to oxygen, which is the final electron acceptor. This process generates a proton gradient across the inner mitochondrial membrane, which is used to drive the synthesis of ATP through oxidative phosphorylation. The respiratory chain consists of four main complexes: Complex I (NADH:ubiquinone oxidoreductase), Complex II (succinate:ubiquinone oxidoreductase), Complex III (ubiquinol:cytochrome c oxidoreductase), and Complex IV (cytochrome c oxidase). Each complex catalyzes a specific step in the electron transport process, with Complex IV being the site of oxygen reduction to water. The respiratory chain is a highly regulated and tightly coupled system, ensuring efficient energy production and maintaining cellular homeostasis.