Cellular respiration is the set of metabolic reactions and processes which occur in cells to convert biochemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products. The type of reactions which take place in respiration are catabolic reactions which consist of the oxidation of one molecule and the reduction of another. In other words, cellular respiration is the process of oxidizing food molecules, like glucose, to carbon dioxide and water. Then the energy released is trapped in the form of ATP for use by all the energy-consuming activities of the cell.
Nutrients commonly used by animal and plant cells in cellular respiration include glucose, amino acids and fatty acids, and a common oxidizing agent (electron acceptor) is molecular oxygen (O2). Bacteria and archaea can also be lithotrophs and these organisms may respire using a broad range of inorganic molecules as electron donors and acceptors, such as sulfur, metal ions, methane or hydrogen. Organisms that use oxygen as a final electron acceptor in respiration are described as aerobic, while those that do not are referred to as anaerobic.
The process of cellular respiration occurs in two phases: 1) glycolysis, the breakdown of glucose to pyruvic acid; 2) the complete oxidation of pyruvic acid to carbon dioxide and water.
Cellular Respiration Animation Video