The final metabolic pathway, which proceeds as a series of chemical reactions in the mitochondria that transfer electrons from the hydrogen atom carriers NAD and FAD to oxygen; water is formed as a by product; the electrochemical energy released by the hydrogen ions is coupled to the formation of ATP from ADP and P.
The electron transport system accounts for the vast majority of adenosine triphosphate (ATP) production in the body. A comprehensive description of the ETS and each of its components is beyond the scope of this book. Briefly, the role of the “chain” of molecules in the ETS is to shuttle electrons from one component in the inner mitochondrial membrane to another via a series of oxidatio-reduction reactions with the ultimate production of ATP from adinosine diphosphate (ADP) as well as water. This process has been termed oxidative phosphorylation. Coenzyme forms of niacin and riboflavin are particularly instrumental in the process, since they serve as the initial electron donators. These molecules are produced in the metabolism of macronutrients by several metabolic pathways including glycolysis, beta-oxidation, and Krebs cycle.
Series of compounds located within the inner membrane of the mitochondrion; high-energy electrons generated in the Krebs cycle pass from com¬ pound to compound, sequentially imparting their energy to each. Energy from the high- energy electrons is used to move protons (H+) from the mitochondrial matrix through the membrane via a proton pump (specialized protein) to the opposite side. Protons that have accumulated outside of the inner membrane then return to the matrix via a specialized enzyme (ATP synthetase). This sequential movement of protons generates a force that, using oxygen, allows ATP synthetase to catalyze chemiosmosis—the reaction that generates adenosine triphosphate (ATP) from adenosine diphosphate (ADP) and also produces water (H2O).