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18 Cards in this Set
- Front
- Back
What are the 2 basic forms of fungi?
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Molds and Yeasts
Molds - cells have the form of branching filaments (hyphae) Yeasts - single round, oval or elongated cells. Multiply by budding or sometimes binary fission. Can form chains (pseudohyphae) |
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What is an aggregated mass of hyphae called?
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Mycelium
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What are the two twpe of hyphae?
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Continuous = aseptate = coenocytic
Septate - divided by septa |
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What are psuedohyphae?
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chains of elongated yeast cells where the buds remain attached to the mother cells.
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What are dimorphic fungi?
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Those that can switch between yeast and mycelial forms
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What are the metabolic characteristics and requirements of fungi?
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All are chemoheterotrophs
Either saprophytic (dead organic matter) or parastic (live organic matter) No obligate anaerobes known. Either obligate aerobes or facultative anaerobes. pH - Usually a preference or at least resistance to acidic media |
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What fungal structure is able to mechanically puncture a plant cell?
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Appressorium
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What does an Appressorium do?
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It is a fungal structure that is able to mechanically puncture a plant cell
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How do fungi utilize polymers and carbohydrates in their surroundings?
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Secrete enzymes extracellularly, then uptake broken down products
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How is growth rate determined for fungi?
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Generation time most efficiently measured in the yeast form. Doubling time anywhere from 1-20 hours.
For molds, growth can be measured as elongation rate of hyphae, or branching rate of hyphae. |
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Where does hyphae growth occur?
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Most growth occurs at tips, leaving the old mycelium empty
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How does fungal sexual reproduction occur?
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In Yeasts and Molds
Yeasts - budding or fission Molds - formation of conidia (spores) |
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What are the types of spores formed in fungi asexual reproduction?
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Sporangiospores - free cells formed inside a sporangium
Conidia (or blastic Conidia) - spores which bud out of the hyphae. Often, the conidia are formed on specialized structures called conidiophores Arthroconidia (thallic conidia) - formed by fragmentation of pre-existing hyphae |
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What are the types of arthroconidia?
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Enteroarthric - every other spore segment forms, and every other space between them is a ghost
Holoarthric - every spore segment forms |
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What are the types of sexual reproduction between fungi called, and what steps does it involve?
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Heterothallic - gametes of different individuals fuse
Homothallic - gametes of the same individual fuse Steps are: 1) Plasmogamy - fusion of 2 cells 2) Karyogamy - fusion of the 2 nuclei 3) Meiosis - reduction division Following meiosis, individual nuclei are incorporated into sexual spores |
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What is the main taxonomic classificaiton of fungi based upon?
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The morphology of the structure which supports sexual spores.
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What are the 4 phyla of "higher" fungi?
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Zygomycota - produce zygospores which result from fusion of two gametangia
Ascomycota - produce ascospores in a "bag" (ascus) Basidiomycota - produce basidiospores, which are borne on a basidium Deuteromycota - no known sexual cycle. Not a real taxanomic class |
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What is the difference between homothallic and heterothallic fungi?
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Homothallic fungi are able to achieve mating even between two cells or hyphae of the same colony/mycelium.
In heterothallic fungi, for mating to occur or to be productive, the cells or hyphae must come from different colonies/mycelia. |