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Fungi Shared Characteristics Distinctive fungal features
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tarix | 23.01.2018 | ölçüsü | 443 b. | | #21888 |
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Fungi
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
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)
- mycelium - mass of connected hyphae
- grows through and penetrates substrate
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
How Fungi Reproduce Differ from most animals and plants in that each compartment of hypha can contain one, two or more nuclei
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
Four Major Groups of Fungi Four major groups - Chytridiomycota
- Zygomycota
- Basidiomycota
- Ascomycota
Chytridiomycota aquatic, flagellated fungi
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
Zygomycota
Ascomycota Very large group including yeasts, common molds, and morels Named for reproductive structure ascus Asexual reproduction takes place in conidia spores at the end of conidiophores.
A moldy orange (left), Penicillium (right)
Ascomycota
Ascomycota Yeasts - unicellular - most reproduction is asexual and takes place by cell fission or budding
- ferment carbohydrates
- play a leading role in genetic research
Basidiomycota Most familiar fungi (mushrooms, toadstools, puffballs, rusts, and smuts) 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.
Gills (reproduction)
Basidiomycota
The life cycle of a mushroom-forming basidiomycete
Ecology of Fungi - lichens - fungi and green algae
- mycorrhizae - fungi and plant roots
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
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
- ectomycorrhizae - hyphae surround, but do not penetrate, cell walls of roots
Mycorrhizae
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