Bio Exam 2 (Charts: Fungus: Chytrids and Zygomycetes)

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  1. Chytrids: Structure
    • Coenocytic, with few septa
    • Has motile cells with a single, posterior, smooth flgellum
    • Some are simple, unicellular organism without a mycelium--> reproductive structure
    • Others have rhizoids that anchor the chytrid
    • Some are parasites of algae, protozoa, oomycetes, etc.
    • Some are saprophytic
  2. Chytrids: Reproduction
    • Intranuclear mitosis and meiosis
    • Alternation of isomorphic generations

    • Others are heteromorphic
  3. Chytrids: Location
    Location: mostly aquatic; soils and banks of ponds and streams
  4. Chytrids: Relevance
    Batrachocytrium dendrobatidis causes a thickening of the skin of amphibians and has caused die-offs of amphibians
  5. Zygomycetes: Structure
    Most have coenocytic hyphae, within which the cytoplasm can be seen streaming rapidly

    Rapidly growing hyphae

    Some can be unicellular and yeastlike

    Rhizopus stolonifer: mycelium has rapidly growing hyphae from which arching hyphae called stolons form; the stolons form rhizoids whenever they come in contact with the substrate-->formation of sporangiophore
  6. Zygomycetes: Reproduction
    • Asexual by means of haploid spores produced in specialized sporangia borne on the hyphae
    • Sexual: formation of zygospores, which develop within thick-walled structures called zygosporangia
    • In any case, the gametangia become separated by formation of septa, and the two multinucleate protoplasts come together
  7. Zygomycetes: Location
    live on decaying plant and animal matter in the soil, while some are parasites
  8. Zygomycetes: Relevance
    • Can cause severe infections in humans and animals
    • Rhizopus stolonifer: black mold hat forms cottony masses on the surface of moist, carb-rich foods like bread, 
    • Parasitic on animals 
  9. 1.       Asexual Life Cycle of Zygomycete (Rhizopus stolonifer)
    mycelium from different haploid hyphae grow --> stolons --> rhizoids --> sporangiophore --> sporangia --> cleavage of protoplast --> sporangiospores --> germination --> mycelium
  10. 1.       Sexual Life Cycle of Zygomycetes
    mycelium from different haploid hyphae grow --> when compatible, they form hormones that lead to growths of peglike structures called progametangium, which come together and form gametangia--> plasmogamy --> nuclei pair --> zygosporangium --> fusion of + and - inside zygosporangium --> diploid zygote (zygospore) --> zygospore dormant --> germination and meiosis --> mycelium
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Bio Exam 2 (Charts: Fungus: Chytrids and Zygomycetes)
2014-03-17 14:48:17
Plant Kingdom
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