What are the different ways in which glucose is oxidized to provide energy various organisms?

A living organism requires energy simply to survive as an organized structure, let alone to perform any useful functions. In this section we explore the chemistry of the major source of the energy used by animals, the oxidation of glucose.

Glucose is first broken down in the cell cytoplasm into a three carbon molecule called pyruvate. Pyruvate is further broken down by different ways to provide energy.

1) Anaerobic respiration: This process takes place in the cytoplasm in the absence of oxygen. Further, the pyruvate may be converted into ethanol and carbon dioxide. This process takes place in yeast.

2) Aerobic respiration: During aerobic respiration, first glucose is broken down into pyruvate and then the three-carbon pyruvate molecule is broken down to give three molecules of carbon dioxide and water. Here the energy relased is much more than anaerobic process.

3) Lack of Oxygen: sometimes, when there is lack of oxygen, especially during vigorous activity, in our muscles, pyruvate is converted into lactic acid (3 carbon molecule compounds). This formation of lactic acid causes cramps.