The Krebs cycle is part of the process used by cells to convert foodstuffs, such as carbohydrates, into usable energy. The cycle was named for Sir Hans Adolf Krebs who first explained its operation in 1936. It is also referred to as the citric acid cycle or the tricarboxylic acid (TCA) cycle. The Krebs cycle has a key role in the metabolism of humans and animals. Metabolism is the sum of all biochemical processes involved in life and is divided into two subcategories: anabolism and catabolism. Anabolism is the building up of large organic molecules from simpler precursors, and catabolism is the breakdown of complex substances into simpler molecules. The Krebs cycle is primarily a catabolic process because it breaks down larger carboxylic acids into smaller units. This process involves oxidative reactions which release chemical free energy; some of this energy is lost as heat and the...