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This 4 page Class Notes was uploaded by Maggie Bruce on Friday October 7, 2016. The Class Notes belongs to BIO 1500 at Wayne State University taught by Thomas Dowling in Fall 2016. Since its upload, it has received 20 views. For similar materials see Basic Life Diversity in Biology at Wayne State University.
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Date Created: 10/07/16
Fungi o Single or multi cellular o Cell walls with chitin o Heterotrophs Use food made by something else Secrete digestive enzymes and then absorb digested materials – external digestion Decomposers – feed on dead organic matter, break down cellulose and lignin Parasites – obtain nutrients from living plants and animals o Asexual and sexual reproduction Asexually usually, by mitosis, when conditions are favorable Sexually when conditions are not favorable to increase genetic diversity Fusion of two haploid hyphae, + and – Zygote, 2n, forms before dikaryon stage Dikaryon stage – when haploid nuclei do not fuse immediately when hyphae fuse, unique to fungi Fungal spore germinates forming hypha Hypha grows and branches into food source Spores are found at the tips of specialized hyphae or in reproductive structures o Long slender filaments – hyphae Cross walls are called septa divide cells that contain one or more nuclei have pores to transport materials Asepatate hyphae lack septa, one long multinucleates cells o Mycelium Mass of concentrated hyphae Grows through and digests cell walls, chitin is more resistant to breakdown than cellulose Found in hard shells of arthropods o More closely related to animals than plants o Monokaryotic – one haploid nucleus per cell o Dikaryotic – two haploid nuclei per cell o Homokaryotic – nuclei are genetically similar, monokaryotic o Heterokaryotic – nuclei are genetically different, dikaryotic o Nuclear mitosis Nuclear envelope does not break down Spindle apparatus forms within nucleus, made of microtubules Spindle plaques take place of centrioles, serve as polar foci Fungal phyla o Eight major phyla o Chytridiomycota aquatic Form haploid and dipolid zoospores Flagellated zoospores Alternation of generation Aseptate hyphae Lack dikaryon stage Form sexual and asexual sporangia Sexual divided by meiosis to form haploid zoospores Asexual divide by mitosis to form diploid zoospores o Zygomycota Produce zygosporangium – thick walled sexual reproductive structure Bread molds Lack septa except when reproducing sexually, forming gametangia Dikaryon stage Plasmogamy – cytoplasm fuses Karyogamy – nuclei fuse o Glomeromycota Form intracellular association with plant roots – arbuscular mycorrhizae Cannot survive without plant Lack septa No evidence of sexual reproduction o Ascomycote Bakers and brewers yeast Common molds Cup fungi morels truffles penicillin form saclike reproductive structure called asci, found in ascocorp asci contain eight ascospores, formed by meiosis and then mitosis have septa dikaryon stage conidia – asexual spores form at the ends of conidiophores multinucleate some are pathogenic – cause diseases chestnut blight dutch elm disease powdery mildew some are unicellular lack hyphae reproduce by budding yeasts o Basidiomycota Mushrooms Puffballs Jelly fungi Shelf fungi Mirror yeasts Club shaped sexual reproductive structure called basidium Mushrooms of genus amanita are poisonous Produce toxins that inhibit RNA polymerase II and III mRNA and tRNA are not produced as a result protein translation cannot occur Some are pathogenic Can affect plants and animals Can cause meningitis in people with HIV o Pathogenic yeast Basidocarp is a basidium bearing structure Pileus is the cap of the mushroom Stipe is the stalk Annulus protects the gills Gills are lined with basidia Basidium is dikaryotic and heterokaryotic Karyogamy produces the zygote Meiosis is used to form the basidiospores Basidiospores form into primary mycelium, monokaryotic Then plasmogamy produces secondary mycelium Fungal Symbioses o Interactions between fungi and other organisms Fungi o Principle decomposers o Break down organic material Symbioses o Obligate – essential for survival o Faculatative – non-essential o Pathogen/parasite – the host suffers, pathogen causes a disease, parasite does not o Commensalism – one partner benefits, the other is not harmed or helped o Mutualism – both partners benefit Mycorrhizae o Mutualistic relationship o Between fungi and plant roots o Allow plants to absorb more roots o Plants provide sugars and organic compounds to fungi o Arbuscular Also called endomycorrhizae Glomeromycetes Hyphae penetrates cell walls of root epidermis and cortex Increases crop yields when there is low phosphate and energy o Ectomycorrhizae Basidiomycetes Hyphae surrounds root and passes between cells of root epidermis and cortex Oaks and pines form these relationships Endophytes o Fungi lives between plant cells o Can be parasitic, commensalistic or mutualistic o Can help plants by producing toxins to keep away predators o Plants give fungi sugars o Live in stems and leaves Animal symbiosis - mutualistic o Leaf-cutter ants have domesticated fungi o Ants give fungi leaves o Ants eat fungi Lichens o Fungi partner with a photosynthetic organism o Usually mutualistic relationships o Fungi protect photosynthetic partner and give them water and minerals o Photosynthetic partners give sugars and organic materials to fungi o Ascomycetes and basidiomycete yeasts o Found in harsh environments o Striking colors due to pigments that protect photosynthetic partners from intense sunlight o Crustose – lichens that grow as crust on surfaces o Fruticose o Foliose Fungal pathogens o Can harm living plants o Can spoil stored food products o Can harm humans Nail fungus Ring worm Athletes foot Caused by imperfect fungi – do not belong to a specific group o Chytridiomycosis Responsible for decline of amphibian populations Causes cardiac arrest by reducing transportation of sodium and potassium across the skin
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