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Fungi. Shared Characteristics Distinctive fungal features – Fungi are heterotrophs. – Fungi have several cell types. – Some fungi have a dikaryon stage.

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Presentation on theme: "Fungi. Shared Characteristics Distinctive fungal features – Fungi are heterotrophs. – Fungi have several cell types. – Some fungi have a dikaryon stage."— Presentation transcript:

1 Fungi

2 Shared Characteristics Distinctive fungal features – Fungi are heterotrophs. – Fungi have several cell types. – Some fungi have a dikaryon stage.  Two haploid cells coexisting in a single cell (dikaryon) before fusion to form nucleus (diploid) – Fungi have cell walls that include chitin. – Fungi undergo nuclear mitosis.  In mitosis, nuclear membrane does not breakdown, mitosis occurs in the nucleus

3 The Body of a Fungus Fungi exist mainly in the form of slender filaments (hyphae). – long chains of cells joined end-to-end divided by cross- walls (septa)  rarely form complete barrier  cytoplasm freely streams in hyphae – mycelium - mass of connected hyphae  grows through and penetrates substrate

4 The Body of a Fungus Fungi cell walls are formed of polysaccharides and chitin. – not cellulose like those of plants Mitosis is unique. – nuclear envelope does not break down and re-form  spindle apparatus formed within  spindle plaques take place of centrioles

5 How Fungi Reproduce Differ from most animals and plants in that each compartment of hypha can contain one, two or more nuclei – monokaryotic - each compartment has a single nucleus – dikaryotic - two distinct nuclei within each hyphae compartment

6 How Fungi Reproduce Fungi are capable of both sexual and asexual reproduction. – Fungi reproduce sexually after two hyphae of opposite mating type fuse.  in some fungi fusion two haploid cells immediately results in diploid cell (2n)  basidiomycetes and ascomycetes have dikaryotic stage (1n + 1n) before parental nuclei fuse to form diploid nucleus

7 Hyphal growth from spore mycelium germinating spore Mycelia have a huge surface area

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9 Four Major Groups of Fungi Four major groups – Chytridiomycota – Zygomycota – Basidiomycota – Ascomycota

10 Chytridiomycota aquatic, flagellated fungi – most closely related to ancestral fungi

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12 Zygomycota includes common bread molds produces temporarily dormant zygosporangia sexual reproduction occurs by fusion of gametangia asexual reproduction most common – hyphae produce clumps of erect stalks - sporangiophores  form sporangia

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16 The life cycle of the zygomycete Rhizopus (black bread mold)

17 Zygomycota

18 Ascomycota Very large group including yeasts, common molds, and morels Named for reproductive structure ascus – haploid zygotic nucleus formed within – asci differentiated with ascocarp Asexual reproduction takes place in conidia spores at the end of conidiophores.

19 A moldy orange (left), Penicillium (right)

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21 Penecillium Conidiophores carrying Conidia

22 Antibiotics المضادات الحيوية

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27 Ascomycota

28 Sac Fungi: Ascomycetes - Life cycle

29 Ascomycota Yeasts – unicellular - most reproduction is asexual and takes place by cell fission or budding  ferment carbohydrates  play a leading role in genetic research

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33 Basidiomycota Most familiar fungi (mushrooms, toadstools, puffballs, rusts, and smuts) – named for characteristic sexual reproductive structure, basidium Four haploid products of meiosis incorporated into basidiospores Mycelium made up of monokaryotic hyphae is called primary mycelium. – fusion of different mating types forms dikaryotic, secondary mycelium.

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35 Gills (reproduction)

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38 Basidiomycota

39 The life cycle of a mushroom-forming basidiomycete

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41 Ecology of Fungi Mutualistic associations – lichens - fungi and green algae – mycorrhizae - fungi and plant roots

42 Lichens Lichens are symbiotic associations between a fungus and a photosynthetic partner. – usually ascomycetes  Specialized fungal hyphae penetrate photosynthetic cells and transfer nutrients to fungal partner.  Durable fungus, combined with photosynthetic properties, has enabled lichens to invade harsh climates. – extremely sensitive to pollutants

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46 Mycorrhizae Roots of about 90% of all kinds of vascular plants are involved in mutualistic symbiotic relationships (mycorrhizae). – arbuscular mycorrhizae - fungal hyphae penetrate outer cells of plant root  most common – ectomycorrhizae - hyphae surround, but do not penetrate, cell walls of roots

47 Mycorrhizae

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