Cellular respiration is a set of metabolic reactions and processes that take place in the cells of organisms to convert chemical energy from oxygen molecules[1] or nutrients into adenosine triphosphate (ATP), and then release waste products.[2] The reactions involved in respiration are catabolic reactions, which break large molecules into smaller ones, releasing energy because weak high-energy bonds, in particular in molecular oxygen,[3] are replaced by stronger bonds in the products.
