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Fungi are unicellular or multicellular thick-cell-walled heterotroph decomposers that eat decaying matter and make tangles of filaments.

KEY POINTS

Fungal cell walls are rigid and contain complex polysaccharides called chitin (adds structural strength) and glucans.

Ergosterol is the steroid molecule in the cell membranes that replaces the cholesterol found in animal cell membranes.

Fungi can be unicellular, multicellular, or dimorphic, which is when the fungi is unicellular or multicellular depending on environmental conditions.

Fungi in the morphological vegetative stage consist of a tangle of slender, thread-like hyphae, whereas the reproductive stage is usually more obvious.

Fungi like to be in a moist and slightly acidic environment; they can grow with or without light or oxygen.

Fungi are saprophyte heterotrophs in that they use dead or decomposing organic matter as a source of carbon.

TERMS

chitin

a complex polysaccharide, a polymer of N-acetylglucosamine, found in the exoskeletons of arthropods and in the cell walls of fungi; thought to be responsible for some forms of asthma in humans

glucan

any polysaccharide that is a polymer of glucose

ergosterol

the functional equivalent of cholesterol found in cell membranes of fungi and some protists, as well as, the steroid precursor of vitamin D2

septum

cell wall division between hyphae of a fungus

mycelium

the vegetative part of any fungus, consisting of a mass of branching, threadlike hyphae, often underground

hypha

a long, branching, filamentous structure of a fungus that is the main mode of vegetative growth

thallus

vegetative body of a fungus

saprophyte

any organism that lives on dead organic matter, as certain fungi and bacteria