Cell walls

The protoplasts of fungal and photosynthetic protistan cells are in most cases surrounded by rigid cell walls. In the  fungi  the  cell wall is composed of a microcrystalline polymer of chitin (repeating units of b1–4-linked NAG) and  amorphous b-glucans, while  in the chlorophyta and some other photosynthetic protista, cell walls are composed of cellulose (repeating units of b1–4-linked glucose) and  hemicelluloses.