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Fungi. Overview Fungi are eukaryotes Most are multicellular Differ from other eukaryotes in nutritional mode, structural organization, growth & reproduction.

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Presentation on theme: "Fungi. Overview Fungi are eukaryotes Most are multicellular Differ from other eukaryotes in nutritional mode, structural organization, growth & reproduction."— Presentation transcript:

1 Fungi

2 Overview Fungi are eukaryotes Most are multicellular Differ from other eukaryotes in nutritional mode, structural organization, growth & reproduction Molecular studies show they are more closely related to animals than to plants

3 Nutrition Absorptive nutrition enables fungi to live as decomposers and symbionts Heterotrophs Acquire nutrition through absorption Digest food outside of their body by secreting hydrolytic enzymes –Exoenzymes –Decompose complex molecules so fungus can absorb them

4 Structural Adaptations Extensive surface area adapts fungi for absorptive nutrition Fungi are constructed of tiny filaments = hyphae –(yeast are an exception) –Hyphae have tubular walls which surround a membrane & cytoplasm –Hyphae are divided into sepatarate cells by septa The hyphae form an interwoven mat = mycelium Fungi have cell walls, most made of chitin –Same material as exoskeleton of insects and arthropods

5 Figure 31.1 Fungal mycelia

6 Figure 31.2 Examples of fungal hyphae

7 Figure 31.2x Septate hyphae (left) and nonseptate hyphae (right)

8 Reproduction Reproduce by releasing spores Spores are produced either sexually or asexually Trillions of spores can be produced by a single organism Dispersed by wind and water over many miles If they land in a receptive spot, grow to form a mycelium

9 The Heterokaryotic Stage Some mycelia become genetically heterogeneous through fusion of 2 hyphae with genetically different nuclei Such a mycelium = heterokaryon Has some of the advantages of diploidy

10 Diversity of Fungi More than 100,000 species are known Four phyla –Chytridiomycota –Zygomycota –Ascomycota –Basidiomycota

11 Zygomycota: Zygote Fungi Live mostly in soil or on decaying plant or animal material One group forms mycorrhizae –mutualistic association with the roots of plants

12 Figure 31.6 The common mold Rhizopus decomposing strawberries

13 Figure 31.7x1 Young zygosporangium

14 Figure 31.7x2 Mature zygosporangium

15 Figure 31.8 Pilobolus aiming its sporangia

16 Figure 31.9 Ascomycetes (sac fungi): Scarlet cup (top left), truffles (bottom left), morel (right)

17 Figure 31.9x1 Carbon fungus

18 Figure 31.9x2 Aspergillus

19 Figure 31.10x1 Life cycle of an ascomycete

20 Figure 31.10x2 Apothecium

21 Figure Basidiomycetes (club fungi): Greville's bolete (top left), turkey tail (bottom left), stinkhorn (right)

22 Figure 31.11x1 Coprinus comatus, Shaggy Mane

23 Figure 31.11x2 Geastrum triplex

24 Figure 31.11x3 Tremella messenterica, Witch’s Butter

25 Figure 31.11x5 Amanita

26 Figure 31.12x Gills

27 Figure A fairy ring

28 Table 31.1 Review of Fungal Phyla

29 Specialized Lifestyles Four types of fungi have developed highly specialized ways of life: Molds Yeasts Lichens Mycorrhizae

30 Molds A rapidly growing, asexually reproducing fungus Mold applies only to the asexual stage Many are destructive, but some are commercially important –penicillin

31 Figure A moldy orange (left), Penicillium (right)

32 Yeasts Unicellular fungi Inhabit liquid or moist habitats Reproduce asexually by budding Used commercially to raise bread and ferment alcohol

33 Figure Budding yeast

34 Mycorrhizae Mutualistic associations of plant roots and fungi Extensions of the fungal mycelium increase the absorptive surface of the plant roots The plant derives minerals absorbed from the soil by the fungus The fungus derives organic nutrients synthesized by the plant Almost all vascular plants have mycorrhizae

35 Figure Mycorrhizae

36 Ecological Impacts Ecosystems depend on fungi as decomposers Provide ecosystems with inorganic nutrients essential to plant growth Recycle carbon, nitrogen, and other elements that otherwise would be tied in organic matter Structure suits function –Invasive hyphae enter tissues of dead organic matter –Exoenzymes can hydrolyze polymers, including cellulose and lignin

37 Figure Examples of fungal diseases of plants: Black stem rust on wheat (left), ergots on rye (right)

38 Figure 31.20x1 Strawberries with Botrytis mold, a plant parasitic fungus

39 Figure 31.20x2 Pink ear rot of corn


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