Glucose are termed glucans. Glucose is produced by plants through the photosynthesis using sunlight, water and carbon dioxide and can be used by all living organisms as an energy and carbon source. However, most glucose does not occur in its free form, but in the form of its polymers, i.e. lactose, sucrose, starch and others which are energy reserve substances, and cellulose and chitin, which are components of the cell wall in plants or fungi and arthropods, respectively. These polymers are degraded to glucose during food intake by animals, fungi and bacteria using enzymes. All animals are also able to produce
Glucose that its hydroxy groups (with the exception of the hydroxy group on the anomeric carbon of -glucose) are in the equatorial position. Presumably, glucose is the most abundant natural monosaccharide because it is less glycated with proteins than other monosaccharides. Another hypothesis is that glucose, being the only D-aldohexose that has all five hydroxy substituents in the equatorial position in the form of β-D-glucose, is more readily accessible to chemical reactions, for example, for esterification or acetal formation. For this reason, D-glucose is also a highly preferred building block in natural polysaccharides (glycans). Polysaccharides that are composed solely of Glucose