Saccharides are divided into monosaccharides, sugars and polysaccharides.

Monosaccharides are divided into five-carbon sugars (ribose and deoxyribose) and six-carbon sugars (glucose, fructose and galactose)

Five-carbon sugars mainly constitute nucleic acids and are found in all cells ( Except for mature red blood cells in mammals); glucose is an energy substance and is present in all cells; fructose is unique to plant cells, and galactose is unique to animal cells, mainly forming polysaccharides.

Disaccharides are divided into plant disaccharides (maltose and sucrose) and animal disaccharides (lactose). Their main function is to hydrolyze energy.

Polysaccharides are divided into plant polysaccharides (starch and cellulose) and animal polysaccharides (glycogen)

Starch is mainly found in storage organs such as seeds, roots, and tubers of food crops. It is a plant The energy storage material of cells; cellulose is mainly found in cotton and linen plants and is a component of the cell wall; glycogen is found in the liver and muscles of animals and is the energy storage material of the animal body.