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Cell Structure and Function 
Because they are eukaryotes, fungi have a sophisticated cellular structure. Fungal cells have 
a membrane-bound nucleus because they are eukaryotes. Some varieties of fungi have structures 
resembling the plasmids (DNA loops) found in bacteria. Additionally, mitochondria and a 
sophisticated network of internal membranes, including the endoplasmic reticulum and Golgi 
apparatus, are found in fungus cells. 
Chloroplasts do not exist in fungus cells. Despite lacking the pigment necessary for 
photosynthetic life, chlorophyll, many fungi exhibit vibrant hues, from red to green to black. Fly 
agaric, a poisonous Amanita muscaria, is distinguished by its bright red cap with white patches 
(Figure 80). Fungi have pigments that are connected to their cell walls and act as an ultraviolet 
radiation shield. Some colors are poisonous. The rigid layers of the fungal cell wall are thick, like 
those of plant cells, but instead of cellulose, which is what plant cells use, they are made of the 
complex polysaccharides chitin and glucan. Chitin, also found in the exoskeleton of insects, gives 
structural strength to the cell walls of fungi. The cell wall guards the cell against drying out and 
predators. Fungi have plasma membranes that are comparable to those of other eukaryotes, with the 
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credit a: modification of work by Chris Wee; credit b: modification of work by Cory 
Zanker; credit c: modification of work by Janice Haney Carr, Robert Simmons, CDC; scale-bar data from Matt Russell

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exception that ergosterol, a steroid molecule that performs similarly to the cholesterol present in 
animal cell membranes, stabilizes the structure. The vast majority of fungi are non-mobile. Only the 
gametes in the archaic division Chytridiomycota can produce flagella.