Glucose Oxidation :Stages of Glucose Oxidation

Glucose Oxidation      Glucose oxidation is the reaction that virtually all cells rely upon for their energy needs. Oxygen reacts with glucose to yield CO2 and water in a reaction that releases energy. The reaction is: C6H12O6 + 6O2 ® 6CO2 + 6H2O + energy      The energy released when glucose is oxidized is done in an incremental fashion and some steps in the metabolic pathway are coupled to the synthesis  of ATP molecules. The total amount of energy released when glucose is oxidized is 686 kcal/mole. Of this 266 kcal is used to synthesize 38 ATP molecules and the remaining 420 kcal is released in the form of heat. Stages of Glucose Oxidation     The oxidation of glucose can be coupled to the synthesis of ATP molecules because it is divided into stages and within these stages energy in the bonds of molecules can incrementally be transferred to the energy in the high energy phosphate bonds of ATP. ATP is the Medium of Energy Exchange      The oxidation of glucose releases 686 kcal/mole. If this energy is not captured in some way it is simply released in the form of heat. Cells harness the energy released by oxidizing glucose by using it to synthesize adenosine triphosphate (ATP).  ATP is synthesized from adenosine diphosphate (ADP) and inorganic phosphate. ADP + Pi + energy ® ATP     This is an example of a condensation reaction because H2O is produced. The energy necessary to move this reaction in the forward direction is 7 kcal/mole. The phosphate group is now covalently bonded with a high energy bond.     The energy in the high energy bond is released when the phosphate group is split from the molecule in a reaction that involves the use of a H2O molecule. This type of reaction is called hydrolysis (hydro- water; lysis- splitting). This reaction is represented as: ATP ® ADP + Pi + energy (H2O is usually omitted from the simplified equation)      Energy is released when this bond is broken and the bond is called a high energy phosphate bond.