The TCA Cycle, also known aas the Krebs Cycle or the Citric Acid Cycle, plays an important role in the production of energy, in synthesis of biomolecules and in the regulation of metabolism. The TCA Cycle is a central pathway in metabolism and is essential for life. All organisms that rely on aerobic respiration, including plants, animals, and most bacteria, use the TCA cycle. The TCA Cycle occurs in the mitochondria, where oxygen is used to complete the cycle. It is composed of eight reactions, each catalysed by a specific enzyme. These reactions convert acetyl CoA into carbon dioxide and water, while producing ATP and NADH.