What Fungi Are Like

What Fungi Are Like

     Fungi are multicellular eukaryotes that are heterotrophic by absorption. After external digestion, they absorb the resulting nutri- ent molecules. Most fungi act as saprotrophic decomposers that aid the cycling of chemicals in ecosystems. Some fungi are parasitic, especially on plants, and others are symbiotic with plant roots and algae.
     The body of a fungus is composed of thin filaments called hyphae, which collectively are termed a mycelium. The cell wall
contains chitin, and the energy reserve is glycogen. Fungi do not have flagella at any stage in their life cycle. Nonseptate hyphae have no cross walls; septate hyphae have cross walls, but there are pores that allow the cytoplasm and even organelles to pass through.
     Fungi produce nonmotile and often windblown spores during both asexual and sexual reproduction. During sexual reproduction hyphae tips fuse so that dikaryotic (n + n) hyphae sometimes result,
depending on the type of fungus. Following nuclear fusion, zygotic meiosis occurs during the production of the sexual spores.