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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
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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)
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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)
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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
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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
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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.
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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
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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
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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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