Fungal cell walls contain chitin, glucans and protein. Unlike plants, they do not contain cellulose. The composition of the cell wall is one of the defining characteristics of fungi.
The fungal cell wall surrounds the fungal cell outside of the plasma membrane. Chitin, which is extruded by the plasma membrane, is the largest component of the wall. Glucans, a type of polysaccharide, give the wall rigidity. Proteins, particularly mannans, reside in the fungal cell wall and work as enzymes to synthesize more of the cell wall. The chitin in the cell wall helps scientists distinguish fungi cells from the cells of plants, bacteria and protists.