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Fungi

Fungi. Basic characteristics of Fungi . Eukaryotic Multicellular (except yeast) Heterotrophic Mode of nutrition: absorbtive Secrete hydrolytic enzymes Digestion occurs externally Composition of cell walls differs-chitin. CHARACTERISTIC. Filamentous Growth Form 1. Hyphae a. stolons

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Fungi

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  1. Fungi

  2. Basic characteristics of Fungi • Eukaryotic • Multicellular (except yeast) • Heterotrophic • Mode of nutrition: absorbtive • Secrete hydrolytic enzymes • Digestion occurs externally • Composition of cell walls differs-chitin

  3. CHARACTERISTIC • Filamentous Growth Form • 1. Hyphae • a. stolons • b. rhizoids • 2. Mycelium • a. If strung end-to-end would be many meters long • b. Surrounds and penetrates substrate • c. Composition of cell wall-Polysaccharide plus chitin (not cellulose) • 1. Same component of arthropod exoskeleton • 2. More resistant to bacterial degradation

  4. Economic Value of Fungi • A.Harmful- Cause decay, rot, spoilage and serious plant and animal diseases • B. Beneficial • 1. Manufacture of bread and beer • 2. Flavor cheese, wine and other foods • 3. Industrial production of acids, antibiotics and chemical syntheses • 4. Detoxify environment • 5. Mycorrhizae facilitate absorption of essential nutrients by plant roots

  5. Fungal Structures • Mycelium: Mostly underground; feeding body composed of interwoven: • Hyphae: threadlike structures • Septa: divide hypae into cells • Haustoria: tips of hyphae • Cell walls: chitin • Some are coenocytic (aseptate) • See fig. 31.1 and 31.2

  6. Life cycle/Reproduction • May be asexual or sexual • Some only have sexual repro in response to an environmental change

  7. ZYGOMYCETES • Structure • a. Hyphae • 1. Stolon-grow horizontally • 2. Rhizoids- grow down • 3. Sporangiophore-grow upward • b. Sporangium(2N) • 1. Form spores(N) • 2. Meiosis

  8. ZYGOMYCETES

  9. BASIDIOMYCETES • 1. Types • a. Mushrooms, jelly fungi, puffballs, rusts and smuts • b. Include edible and poisonous varieties • 2. Reproduction • a. Sexual • b. Asexual reproduction rare in basidiomycetes • 3. Structures • a. Stipe • b. Gills • c. Cap • d. Annulus

  10. BASIDIOMYCETES

  11. ASCOMYCETES • 1. Types • a. Beneficial forms include yeast, penicillin, morels and truffles, cheese mold, neurospera • b. Harmful forms include chestnut blight, Dutch elm disease, Clavis purpurea-LSD • c. Reproduction • 1. Asexual reproduction is common • 2. Sexual

  12. ASCOMYCETES

  13. DEUTEROMYCETES • 1. Fungi that Have Lost the Ability to Reproduce Sexually • 2. Have great economic importance • a. Many are human and plant pathogens • 1. ring worm • 2. athletes foot • b. Others produce important chemicals including penicillin • V. Fungal Relatives

  14. MYCORRHIZAE • b. Mycorrhizae • 1. General characteristics • a. Most plant roots associated with certain fungi • b. Fungus aids in transfer of soil nutrients into roots • c. Plant provides organic carbon to fungus • 2. Advantages of mycorrhizial associations • a. Plants more resistant to drought, cold and harsh conditions • b. May provide better protection against acid precipitation • c. Prevent accumulation of toxic metals • d. Speed germination of orchid seeds • e. Provide better growth in poor soils • f. Present in early fossil plants • g. Early soil lacking organic matter

  15. FUNGAL RELATIVES • A. Lichens • 1. General Characteristics • a. Mostly ascomycetes with green alga and/or cyanobacterium • b. Specialized hyphae penetrate or envelop photosynthetic cells • c. Fungal chemical signals direct photosynthetic metabolism • d. Could be considered a form of controlled parasitism • 2. Reproduction • a. Via normal fungal sexual processes • b. Photosynthetic cell reproduction generally asexual • c. Asexual reproduction by fragmentation

  16. 3. Ecology • a. Inhabit cold, dry, generally harsh environments b. Help break rock surfaces and prepare habitat for other organisms • c. Lichens with cyanobacteria can fix atmospheric nitrogen • d. Survive adverse conditions by nearly halting metabolism • e. First growth on barren rock-leads to soil • 4. Lichens and Pollution • a. Extremely sensitive to atmospheric pollutants • b. Absorb substances dissolved in rain or dew • c. Sensitive to sulfur dioxide an automobile pollutant • d. Indicates radioactive pollution

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