But rather than a straight chain of glucose units, glycogen is a more highly branched chain of glucose molecules. Glycogen is the main energy reserve in animals. Cellulose is yet a third polymer of the monosaccharide glucose. Since plants do not have bones to provide support for the plant, cellulose is used as a structural molecule to support leaves and other plant parts. Despite the fact that it cannot be used as an energy source in most animals, cellulose in the diet is often referred to as dietary fiber.
Fiber helps exercise the digestive track and keep it clean and healthy.
Fats Fats are a sub-group of compounds found in living organisms that are insoluble in water known as lipids. First, fats can be used as a reserve, or long-term, source of energy in animals. During periods of low food consumption, fat reserves in the body can be mobilized and broken down to release energy. Fats serve as an insulation material to allow body heat to be conserved and also lining and protecting delicate internal organs from physical damage. In addition, fats are essential to the proper maintenance of cell membranes in the body and are used in the production of certain hormones and steroids.