There is a fungus among us!!!!!!

 A eukaryotic, heterotrophic organism devoid of chlorophyll that obtains its nutrients by absorption, and reproduces by spores.

 1. All are eukaryotic Possess membrane-bound nuclei (containing chromosomes) and a range of membrane-bound cytoplasmic organelles (e.g. mitochondria, vacuoles, endoplasmic reticulum).  2. Most are filamentous Composed of individual microscopic filaments called hyphae, which exhibit apical growth and which branch to form a network of hyphae called a mycelium.hyphae mycelium  3. Some are unicellular e.g. yeasts.yeasts  4. Protoplasm of a hypha or cell is surrounded by a rigid wall Composed primarily of chitin and glucans, although the walls of some species contain cellulose.  5. Many reproduce both sexually and asexually Both sexual and asexual reproduction often result in the production of spores.sexualasexual  6. Their nuclei are typically haploid and hyphal compartments are often multinucleate Although the Oomycota and some yeasts possess diploid nuclei.  7. All are achlorophyllous They lack chlorophyll pigments and are incapable of photosynthesis.  8. All are chemoheterotrophic (chemo-organotrophic) They utilise pre-existing organic sources of carbon in their environment and the energy from chemical reactions to sythesise the organic compounds they require for growth and energy.  9. Possess characteristic range of storage compounds e.g. trehalose, glycogen, sugar alcohols and lipids.trehalose  10. May be free-living or may form intimate relationships with other organisms i.e. may be free-living, parasitic or mutualistic (symbiotic).

 Fungi=absorptive heterotrophs  Animals=phagotrophic heterotroph  Heterotroph (chemo-organotrophs): an organism incapable of synthesizing carbohydrates from inorganic sources; requires preformed organic compounds produced by other organisms  Plants=autotrophs

 Cylindrical, branching filaments composed of a tubular cell wall filled with cytoplasm and organelles  Most fungal hyphae are 2-10  m diameter

 Septa—regular cross-walls formed in hyphae. Hyphae with septa are septate, those lacking septa are aseptate or coenocytic.  primary septa are formed as a process of hyphal extension and generally have a septal pore, which allows for cytoplasmic and organelle movement.  Secondary or adventitious septa are imperforate, formed to wall off ageing parts of the mycelium.

 Chytridiomycota—lack true hyphae – pretty diverse  Zygomycota—coenocytic hyphae  Zygote fungi – terrestrial and fast growing  Bread mold (Rhizopus)  Glomeromycota—coenocytic hyphae  mycorrhizae – sympiotic relationship between roots of plant and fungus  Ascomycota—septate hyphae  Spores located in “asci”  Yeasts (Neurospora)  Sordaria – ap lab 3  Basidiomycota—septate hyphae  Club fungi – typical mushroom  Deuteromycota –  Most Penicillium

 Small genome relative to other eukaryotes  Many fungal genes are homologous to those in other eukaryotes  Easy to grow, short life cycles  Haploid genomes amenable to mutation  Sexual stage for analysis of segregation and recombination of genes; all products of meiosis can be retrieved in haploid spores  Asexual (clonal) reproduction

 Many fungi have the ability to reproduce by asexual and sexual means

 Phyla:  Chytridiomycota  Form motile spores called zoospores  Meiosis occurs in resting sporangium  Glomeromycota  Form spores containing hundreds of nuclei; no known sexual reproduction  Zygomycota  Form asexual spores called sporangiospores  Meiosis occurs in zygospore  Ascomycota (including Deuteromycetes)  Form asexual spores called conidia  Meiosis occurs in ascus  Basidiomycota  Meiosis occurs in basidium

 The vegetative thallus predominates in the life cycle of a fungus  The thallus may be haploid (1n), dikaryotic (n+n) or diploid (2n) in different groups of fungi  Ploidy of thallus is determined by the timing of these events in the life cycle:  Plasmogamy (cell fusion)  Karyogamy (nuclear fusion)  Meiosis (reduction division)