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Fungi

Fungi. Section 18-2. What is a Fungus?. They are heterotrophic eukaryotes with a cell wall They obtain food by extracellular digestion and absorption Enzymes are released to break down food particles outside their bodies Digested molecules are then absorbed. What is a Fungus?.

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Fungi

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  1. Fungi Section 18-2

  2. What is a Fungus? • They are heterotrophic eukaryotes with a cell wall • They obtain food by extracellular digestion and absorption • Enzymes are released to break down food particles outside their bodies • Digested molecules are then absorbed

  3. What is a Fungus? • Most are multicellular (except yeast) • Can be parasitic or decomposers • They look more like plants, but are technically more like animals: • They have cell walls like plants, but the cell wall is made of chitin not cellulose (chitin is found in the exoskeletons of insects) • They store energy as the starch glycogen, like animals and are heterotrophic

  4. Characteristics of Fungi • Evolved around 430 million years ago • All multicellular fungi have the same basic structure: • Hypha (pl. hyphae) – a threadlike filament whose cells have varying numbers of nuclei • Mycelium – mass of hyphae that grows into the food source (this is the part that secretes the enzymes for digestion) • Fruiting body – the reproductive part of the fungus that produces spores

  5. Reproduction in Fungi • Can be asexual: • Some produce spores • Some reproduce by fragmentation of hyphae

  6. Reproduction in Fungi • Can be sexual: • There are two mating types - + hyphae and – hyphae • When opposite hyphae meet, some of their filaments fuse • Their nuclei then fuse, undergo meiosis, and produce spores

  7. Types of Fungi • Phylum Zygomycota (called zygomycetes) • Also called bread molds or common molds • Reproduction has two phases, one asexual and one sexual • An example is Rhizopus stolonifer (black mold)

  8. Types of Fungi • Phylum Ascomycota (called ascomycetes) • Also called sac fungi • 30,000+ species of mildews, molds, and yeasts • Examples include truffles, baker’s yeast

  9. Types of Fungi • Phylum Basidiomycota (called basidiomycetes) • Fruiting bodies form mushrooms (above ground) • Many are delicious, some can be poisonous

  10. Types of Fungi • Phylum Deuteromycota (called deuteromycetes) • Also called “imperfect” fungi because scientists have never been able to identify the sexual stage of their life cycle • Example is Penicillium, which is used to make the antibiotic penicillin; also the fungus that causes athlete’s foot

  11. Lichens • Look like moss, usually seen growing on tree trunks or rocks • Not actually a single organism – represents a symbiotic partnership between a fungus and some photosynthetic organism, like a bacterium or algae • The autotroph performs photosynthesis, which provides nourishment for the fungus • The fungus provides the autotroph with water and minerals that it removes from the rock or the tree

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