glucose

Simple sugar present in the blood and manufactured by green plants during photosynthesis. It belongs to the group of chemicals known as carbohydrates. The respiration reactions inside cells involves the oxidation of glucose to produce ATP, the ‘energy molecule’ used to drive many of the body's biochemical reactions.

As well as being used in respiration to release useful energy glucose may also be transported to specific parts of the body for other uses. The liver and muscles can turn it into glycogen, which acts as an energy store. It can also be turned into fat and stored in fatty tissue. In humans and other vertebrates optimum blood glucose levels are maintained by the hormone insulin. An inability to control glucose levels may be caused by the disease diabetes.

Green plants make glucose during photosynthesis. They can turn it into starch, which acts as an energy store and this starch may form an important part of the human diet.

Glucose is prepared in syrup form by the hydrolysis of cane sugar or starch, and may be purified to a white crystalline powder. Glucose is a monosaccharide sugar (made up of a single sugar unit), unlike the more familiar sucrose (cane or beet sugar), which is a disaccharide (made up of two sugar units: glucose and fructose).