Chitin is a derivative of glucose, and is a characteristic component of the cell walls of fungi, the exoskeletons of arthropods such as crustaceans (e.g., crabs, lobsters and shrimps) and insects. Cellulose, an insoluble substance, is the main constituent of plant cell walls and of vegetable fibres such as cotton. It is type of a polysaccharide which consists of chains of glucose monomers. In animals glycogen is stored in liver and muscles. Starch is found in plants e.g., potato.

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