Respiration is the process of oxidation of glucose into CO2 and H2O releasing energy in form of heat and ATP. First the glucose molecules undergo glycolysis in which the glucose is enzymatically degradation into pyruvic acid.
Pyruvic acid is the principal intermediate compound which can undergo both in case of former ethyl alcohol or lactic acid are formed, where as aerobic oxidation is a complicated biochemical degradation process, which called tricarboxylic acid cycle or kreb’s cycle or citric acid cycle. It takes place inside the mitochondria of living cell.
It involves following steps of reactions in a cyclic process (I) pyruvic acid reacts with CoA and NAD and is oxidatively decarboxylated.
One molecule of CO2 is released and NAD is reduced pyruvic acid is converted into acetyl -CoA.