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Fungi
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Fungi basidomycete, ascomycete mold, chytrid, Aspergillus sp.
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Fungi characteristics
Fungi are sessile heterotrophs Important both ecologically and economically Secrete enzymes which break down food and then absorb the food some do this in the environment some penetrate cells of other organisms and absorb nutrients from cells
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Structure Either multicellular or unicellular (yeast)
some yeast are sort of multicellular because they connect in strings forming “pseudohyphae” (many molds) Most multicellular fungi have hyphae – cells surrounded by a tubular cell wall made of chitin. The primary structure of fungi In most fungi, the mass of all non-sexual hyphae is called a “mycelium”. In mushrooms, the sexual part is the above ground part. Many mycelium are underground most hyphae are divided by cross walls called septa that divide the hyphae Septa have pores that allow many parts of the cells to flow back and forth between cells on either side of the septum
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from mitosis w/o cytokinesis
mycorrhizae specialized hyphae that allow absorption from other organisms
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Mycorrhizae symbiosis between fungus and plants (at the roots)
plants provide constant source of carbs (glucose) fungus provides ability to fix nutrients like nitrogen so they may be absorbed. legumes found in many plants
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Fungi
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Evolution of Fungi
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“Arbuscular mycorrhizal”
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“AM” - many are parasitic - chytridiomycosis major cause of
amphibian decline worldwide Chitosan instead of chitin specialized spores bread mold 230 species mycorrhizae “AM” -brewers yeast, bakers yeast, Penicillium, morels, truffles. -much evidence to support monophyly -posses “ascospores” for reproduction Septate - most of the familiar fungi – all the muschrooms, smuts, rusts, puff balls,etc. - reproduce via basidia (specialized reproductive cells)
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Reproduction As part of their life cycle, fungi produce spores.
spores are tough reproductive cells but much variation One common process: Spores produced by meiosis are carried on a clublike sporangium. From these spores, haploid hyphae grow, and may give rise to asexual sporangia, special hyphae which produce spores without meiosis.
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Reproduction Plasmogamy – Cytoplasm of 2 parent mycelia join
Karyogamy – Haploid nuclei from two parents fuse to produce diploid cells. Cells with one cytoplasm and two nuclei are known as a dikaryon; meaning "two nuclei". Also called ‘heterokaryotic’.
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Reproduction
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Reproduction no fusion of nuclei!
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Reproduction
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Chytrids aquatic microscopic flagellate reproductive cells
sometimes including in the water trapped around soil particles microscopic flagellate reproductive cells lost in later fungi (doesn’t work well on land)
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Zygomycetes (bread molds) named for large zygotes known as zygospores
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Ascomycetes (yeasts, Penicillium)
Neurospora crassa George W. Beadle and Edward L. Tatum Showed that genes (proteins) control metabolic processes.
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Basidiomycetes
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Yeasts (Ascomycota and Basidiomycota)
Ascomycota contains the “true yeast”
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Yeast characteristics
Single celled Reproduction by budding or binary fission E.g. yeast in baking Saccharomyces cerevisiae E.g. Candida albicans pathogenic to humans
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“AM” (Glomeromycetes)
~80% of plant species form symbiosis with
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Lichens Lichen – A symbiotic relationship between a fungi and a photosynthetic microorganism Fungi form with green algae or cyanobacterium Mostly Ascomycetes
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Lichens (Ascomycetes)
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