<Tr> <Td_colspan="2"> Infobox references </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> </Tr> <P> Glucose is a simple sugar with the molecular formula C H O. Glucose circulates in the blood of animals as blood sugar . It is made during photosynthesis from water and carbon dioxide, using energy from sunlight . It is the most important source of energy for cellular respiration . Glucose is stored as a polymer, in plants as starch and in animals as glycogen . </P> <P> With six carbon atoms, it is classed as a hexose, a subcategory of the monosaccharides . D - Glucose is one of the sixteen aldohexose stereoisomers . The D - isomer, D - glucose, also known as dextrose, occurs widely in nature, but the L - isomer, L - glucose, does not . Glucose can be obtained by hydrolysis of carbohydrates such as milk sugar (lactose), cane sugar (sucrose), maltose, cellulose, glycogen, etc . It is commonly commercially manufactured from cornstarch by hydrolysis via pressurized steaming at controlled pH in a jet followed by further enzymatic depolymerization . Unbonded glucose is one of the main ingredients of honey . </P>

Where do the 6 carbon atoms in glucose come from