Citric Acid Cycle
Citric Acid Cycle, series of chemical reactions occurring within the cell, responsible for the final breakdown of food molecules to form carbon dioxide, water, and energy. This process, which is carried out by seven enzymes , is also known as the tricarboxylic acid cycle, or the Krebs cycle. The citric acid cycle is active in all animals and higher plants and in most bacteria. In organisms that have cells with nuclei, the cycle is contained within a membrane-bound organelle called the mitochondrion, a structure often referred to as the power plant of the cell . Discovery of the citric acid cycle is credited to Sir Hans Adolf Krebs, a British biochemist who outlined its essential steps in 1937. Before a food can enter the citric acid cycle, it must be broken down into small units called acetyl groups. Each acetyl group (CH3CO) contains only two atoms of carbon, along with hydrogen and oxygen. At the start of the cycle, an acetyl group combines with a four-carbon molecule called oxaloace