tricarboxylic acid cycle the cyclic metabolic mechanism by which the complete oxidation of the acetyl portion of acetyl-coenzyme A is effected; the process is the chief source of mammalian energy, during which carbon chains of sugars, fatty acids, and amino acids are metabolized to yield carbon dioxide, water, and high-energy phosphate bonds. Called also citric acid cycle and Krebs cycle . Click here to view image Tricarboxylic acid cycle. Diagrammatic representation of reactions by which carbon chains of sugars, fatty acids, and amino acids are metabolized to yield carbon dioxide. Water produced by the cycle and components of the high-energy phosphate pool generated by the associated electron chain are not shown.