Carbohydrates are one of the four major organic compounds. They are made up of carbon, hydrogen and oxygen. Carbohydrate macromolecules are called polysaccharides. The subunits of polysaccharides are monosaccharides (eg. glucose) and disaccharides (eg. sucrose). The four important polysaccharides in cells are cellulose, starch, glycogen and chitin. Cellulose and chitin perform structural roles in some types of cells. Starch and glycogen perform functional roles (energy storage) in plants and animals respectively. For more Biology video lessons check out www.anytimeeducation.com