Like plants, fungi have cell walls. The cell walls of fungi are made of chitin, the same substance that makes up the exoskeletons of arthropods such as insects, according to The State University of New York. The cell walls of similar organisms are made of cellulose.
The Canolfan Edward Llwyd Centre for Bilingual Science states that the cell walls of fungi cells keep the cell intact during the osmosis process. The cell wall contains a strong mesh made of chitin, glucose polymers called glucans, a variety of different proteins and a black pigment called melanin that helps prevent damage from ultraviolet radiation.