The CALVIN-BENSON Cycle : The CALVIN-BENSON Cycle What is Calvin Benson Cycle? : What is Calvin Benson Cycle? The light-independent Calvin cycle
uses the energy from short-lived electronically-excited carriers to convert carbon dioxide and water into organic compounds
known as the "dark reaction" or "dark
stage," Slide 3: This helps plants to process the 5 carbon sugar or what we called “pentose” and water into sugar and organic materials. The enzymes in the Calvin cycle are functionally equivalent to many enzymes used in other metabolic pathways such as gluconeogenesis and the pentose phosphate pathway, but they are to be found in the chloroplast stroma instead of the cell cytoplasm, separating the reactions. They are activated in the light (which is why the name "dark reaction" is misleading), and also by products of the light-dependent reaction. These regulatory functions prevent the Calvin cycle from being respired to carbon dioxide. Energy (in the form of ATP) would be wasted in carrying out these reactions that have no net productivity. THE CALVIN BENSON CYCLE : THE CALVIN BENSON CYCLE It should be noted that hexose (six-carbon) sugars are not a product of the Calvin cycle. Although many texts list a product of photosynthesis as C6H12O6, this is mainly a convenience to counter the equation of respiration, where six-carbon sugars are oxidized in mitochondria. The carbohydrate products of the Calvin Cycle are three-carbon sugar phosphate molecules, or "triose phosphates," to be specific, glyceraldehyde-3-phosphate (G3P).