Chapter 31

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  1. Gernal Fungal Characteristics
    • Fungi are heterotrophs that feed by absorption
    • Most secrete enzymes that allow:
    •      Decomposition of dead organic matter
    •      Large molecules broken down and absorbed
    •      Act as decomposers
    • Some penetrate tissues of living host
    •      Can be parasitic and cause disease (pathogens)
    •      Can be mutualistic and benefit
  2. Fungi Body Structure
    • Can be multicellular and/or single-celled
    •      Ex. Yeasts are single-celled fungi
    • Multicelled bodies are a filament network
    •      Individual filaments are called hyphae
    •           Hyphal cells divided by septa
    •                Some species lack septa and are coenocytic
    •           The filament network is called a mycelium
    • Cell Wall is present
    •      Made of chitin (vs. cellulose in plants)
  3. Fungal Reproduction
    • Produce large numbers of spores
    •      Through sexual and/or asexual cycles
    • Sexual reproduction
    •      Hyphae (n) release sexual pheromones
    •           Requires two different mating types (+/-)
    • Hyphae fuse together and cytoplasm unites
    •      Called plasmogamy
    • Nuclei may not immediately fuse
    •      Cells remain dikaryotic (n + n) (heterokaryotic)
    • Sexual Reproduction (cont)
    •      Late karyogamy occurs and nuceli fuse (2n)
    •           Zygote (2n) undergoes meiosis
    •                Produces spores (n)
    •           Spores germinate to form new mycelium
    • Asexual reproduction
    •      Spores are produced by mitosis (vs. Meiosis)
  4. Fungal Diversity-- Chytrids
    • Ubiquitous (lakes and moist soil etc.)
    • Many decomposers and parasites
    •      Some are animal digestive mutualists
    • Have flagellated spores
    •      Called zoospores
    •      Unique among fungi
  5. Zygomycetes
    • Many fast growing molds (like bread mold)
    • Named for characteristic zygosporangium
    •      Sexual sporangium
    •      Resistant to many environmental extremes
    •           REmain dormant until favorable conditions return
    • Many interesting asexual sporangia also
    •      Ex. Pilobolus Sporangia can track light
    •           Shoot spores towards light source
  6. Glomeromycetes
    • Mostly mycorrhizal fungi
    •      Called arbuscular mycorrhizae
    •      Form arbuscles
    •           Specialized hyphae that penetrate plant cells
    • Form mutualistic relationships with ~90% of plant species
    •      Connect with plant roots in soil.
  7. Ascomycetes
    • Called Sac fungi
    • Form sac-like asci to produce ascospores
    •      Sexual spore
    •      Fruiting body called ascocarp
    •           Often cup-shaped
    • Also reproduce with conidia
    •      Asexual spores borne on condiospores
    •      Produced on the tips of specialized hyphae
  8. Basidiomycetes
    • Called the club fungi
    • Karyogamy occurs in specialized cell
    •      Called the basidium
    • Fruiting bodies are basidiocarps
    •      Many are commonly called mushrooms
    •           Spores of mushrooms are produced on gills
    •           Gound on the underside of the cap
  9. Lichen
    • Symbiotic relationship between fungas and cynobacteria or green algae.
    • Photosymbiont lives in hyphal mass
    •      Provides sugars from photosynthesis
    •      Receives shelter, water, minerals
    • Reproduction by formation of soredia
    •      Clusters of hypae with embedded symbiont
    • Foliose, fruticose, and crustose forms
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Chapter 31
2012-10-13 21:50:19

Exam 2
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