The Krebs cycle, also referred to as the Citric Acid cycle, is the process during which humans and animals break down and metabolize carbohydrates, proteins and fats. This cycle produces carbon dioxide, water and high-energy phosphate molecules.
The Krebs cycle is a chemical process that takes place in the mitochondrial matrix of living cells in aerobic organisms. Aerobic organisms need oxygen to grow and survive and include humans and most animals. Some types of fungi are also aerobic. The inner membrane of the mitochondrion contains the mitochondrial matrix, which has the enzymes used during the Krebs cycle that produce adenosine triphosphate.
During the Krebs cycle, carbohydrates, proteins and fats combine with oxygen to produce carbon dioxide and water as waste and ATP, which cells use for energy. The Krebs cycle is sometimes called the Citric Acid cycle because the cycle begins by producing citric acid, the chemical needed to break down carbohydrates, proteins and fat, and ends with the production of more citric acid, preparing the body for another Krebs cycle.
The combination of Acetyl-CoA molecules with the chemical compound ocaloacetate creates citric acid. Each molecule of Acetyl-CoA that enters the cycle produces two molecules of carbon dioxide, and both are given off as waste.