Fungi - Fungi 1) Nutrition a) Diverse- but nutrition...

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Fungi 1) Nutrition a) Diverse- but nutrition similar ways b) Fungi are heterotrophs c) Fungi don’t “eat” food they secrete exoenzymes into surroundings and break down complex molecules into smaller molecules, then they absorb smaller molecules. d) Diverse lifestyle as decomposers, parasites, mutualists e) High surface area to volume ratio of mycelia enhances feeding efficiency. i) Hyphae have tubular cell walls ii) Cell walls contain chitin ( chitin is also found in insect exoskeleton) iii) Septa divide cells iv) Fungi without septa are coenocytic v) Hyphae are specialized to trap and kill prey and to penetrate host tissue(“haustoria”). (1) Parasitic fungi (2) Mutualistic fungi mycorrhizae (“fungus roots”) (a) Ectomycorrhizar: hyphae form on root surface (b) Endomycorrhizae: extend hyphae through root cell wall. (c) Mycorrhizal associations: (i) Mutualism(+/+)= plant obtains nutrients (phosphorus, nitrogen, minerals), fungus obtains organic compounds (photosynthate) 2) Reproduction a) Reproductive cells are spores i) Sexual spores
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ii) Asexual spores iii) Dispersed by wind and water b) Nuclei and spores are haploid c) Diploid stage is transient d) Fungi reproduce by releasing spores that are produced either sexually or asexually. The output of spores from one reproductive structure is enormous, with the number reaching into the trillions. Spores are dispersed widely by wind or water, spores germinate to produce mycelia if they land in a moist place where there is food. e) Generalized sexual reproduction: Hyphae from 2 different mycelia fuse, mycelia are now heterokaryotic (“different nuclei”) . . .time passes and the union of haploid nuclei (diploid zygote is produced), meiosis produces spore-producing structures (haploid). . . see Slide 21 f) Generalized asexual life cycle: spores germinate and form mycelia, mycelia produce spore –producing structures (e.g. puff balls), spores germinate, cycle repeats i) All structures are haploid ii) Asexual reproduction is common in: molds, yeasts: cell division or “budding” (small portion of parent cell pinches off) 3) Evolutionary relationships a) Phylogenic evidence suggests that fungi evolved from a flagellated, unicellular ancestor b) Molecular clock suggests that animals and fungi diverged 1.5 billion years ago
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This note was uploaded on 03/31/2008 for the course EBIO 1220 taught by Professor Demig-addams during the Spring '07 term at Colorado.

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Fungi - Fungi 1) Nutrition a) Diverse- but nutrition...

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