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Kingdom Fungi What is probably the largest living organism on earth has been discovered in the Malheur National Forest in eastern Oregon. A fungus living three feet underground is estimated to cover 2,200 acres. After testing samples from various locations, scientists say it is all one organism. Officially known as Armillaria ostoyae, or the honey mushroom, the fungus is 3.5 miles across and takes up 1,665 football fields. The small mushrooms visible above ground are only the tip of the iceberg. Experts estimate that the giant mushroom is at least 2,400 years old, but could be 7,200 years old. The Study of Fungi is called Mycology
Characteristics of Kingdom Fungi In order to belong to the Kingdom Fungi, organisms must: • Be Multicellular • Have Eukaryotic cells • Be Heterotrophs • Must have cell walls • Most fungi are sedentary..(they don’t move around, they live their lives anchored somewhere)
Cell Walls • The cell walls of Fungi are made of Chitin (Chitin is a sugar… the same substance which makes up the exoskeleton of insects) • Some fungi have cross walls, or septa, which divide the filaments into compartments having a single nucleus. septum
Some cells lack septa and are multi-nucleated, or coenocytic (have many nuclei)
Digestion takes place outside the body (extra-cellular) • Fungi are Absorptive Feeders …they simply ingest (absorb) digested foods thru their cell walls
Facts • Fungi live and grow in their food • only seen when the fruiting bodies emerge…. By then it’s too late
Facts • Cell Walls are either partial or absent………. The cytosol is circulated through simple cyclosis.
Ecological Role • The major role of Fungi is as Decomposers (they are the great recyclers)…. They are Saprophytes
The Primary Structures of a Fungi • Spores Hypha Mycelium Fruiting Body (haploid reproductive cell) (a single filament) (a mass of hyphae) (reproductive and dispersion)
Spore with Developing Hypha**(some fungi have haustoria, hyphae that can penetrate their host) Spore Hypha
The Hypha begins to branch as it digests its way through the food.
Fungi spend most of their time as haploid (n) organisms. However, most form a temporary diploid structure for reproduction. The three following stages occur during sexual reproduction…. plasmogamy, karyogamy and meiosis.
Plasmogamy is the fusion of two haploid cells from two separate fungi strains. The fusion forms a dikaryon (a cell with the two haploid nuclei). A hypha containing a dikaryon is called a dikaryotic hypha.
Karyogamy is the fusing of the two haploid nuclei of a dikaryon to form a single diploid nucleus.
Meiosis of the diploid nucleus restores the haploid number. n 2n n
Fungi Reproduction • Fungi reproduce both sexually and asexually. • Asexual reproduction includes: 1. fragmentation: the breaking up of hypha 2. budding: the pinching off of a small hypha outgrowth 3. asexual spores: there’s two kinds of asexual spores a. Sporangiospores are produced by sporangia which are located on top of a filament called a sporangiophore. b. Conidia are formed at the tips of specialized hyphae called conidiophores.
Asexual Spores Sporangium: Produces the sporangiospores Sporangiophore: Holds up the sporangium
Asexual Spores The Conidiophores look like tubes… the conidia look like small black dots inside the tubes.
Classification of Fungimostly classified by the shape of the “Fruiting Bodies”The “Fruiting Bodies” are the reproductive structures. • Phylum Zygomycota (bread mold) • Phylum Basidiomycota (mushrooms, puff balls, bracket fungi) • Phylum Ascomycota (cup fungi) • Phylum Deuteromycota (Imperfect fungi)
Phylum ZygomycotaA common Zygomycota is Bread Mold Hyphae lack septa Sexual reproduction is by conjugation (fusing) hyphae from two different strains, followed by plasmogamy, karyogamy and meiosis and the production of Zygospores.
Zygomycota Sporangium: Produces the spores Sporangiophore: Holds up the sporangium
Phylum Basidiomycota • Mushrooms • Puffballs • Shelf (Bracket) Fungi • Have Septa and reproduce sexually • Underground hyphae intertwine and grow upward to produce a reproductive structure called a basidiocarp. This basidiocarp is what we call a mushroom. • Basidiospores are produced on the basidia, reproductive structures, which are found on the edges of the gills.
Phylum Ascomycota • Cup Fungi • Yeast • Mildews • The largest group of fungi • Named for the reproductive sacs or Asci that form near the tips of the hyphae. Ascospores are formed here and released into the air when the ascus ruptures. These spores germinate to form new hyphae.
Phylum Deuteromycota • Athlete’s Foot • Ringworm • Penicillium • Called “imperfect because a sexual reproductive stage has not been observed.
