Ch31 Fungi

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Ch31 Fungi
2011-03-21 11:44:33

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  1. Supergrp Opisthokonta (Eukaryote)

    Kingdom Fungi
    Kingdon Animalia
    Fungi arose from protists related to an amoeba that feeds by engulfing cells
  2. Fungi are related to animals:
    • Both heterotrophic- cannot produce their own food
    • Both use absorptive nutrition-secrete enzymes and absorb resulting small organic molecules
    • Both store surplus food as carb glycogen
  3. Unique cell-wall Chemistry
    • Fungi cells enclosed by tough cell walls composed of chitin
    • Cells cannot engulf food due to rigid walls
    • Cell walls restricts mobility of nonflagellate cells
  4. Unique body form:
    • Most hv mycelia composed of hypae
    • Fruiting bodies r visible reproductive structures (produce spores)

    IE: Mushrooms
  5. Distinctive growth processes:
    • Mycelia can grow quickly whn food is plentiful
    • Grow at the edge
    • Narrow dimensions and extensive branching provides high surface area for absorption
    • Osmosis impt in growth-entry of water produces force for tip extensions
  6. Septate fungi
    • Septa- Cross walls dividing cells of mycelium
    • Each cell has 1 or 2 nuclei
    • Nuclear division followed by cross-wall formation
  7. Aseptate Fungi
    • Not partitioned into smaller cells
    • Multinucleate
    • Nuclei divide wo cytokinesis
    • Coenocytic
  8. Asexual Reproduction:
    • Reproduce both sexually and asexually by spores
    • Many reproduce only asexually
    • Conidia-asexual spores at tips of hypae
  9. Sexual Reproduction:
    • Involves union of gametes, zygote formation and meiosis
    • Gametes of most fungai r cells of hyphal branches
    • Mating types differ biochemically
    • Hyphal branches fuse bwn compatible mating types
    • Most hv plasmogamy (fusionof gametes' cytoplasm
    • Mycelium is diakaryotic or heterokaryotic
    • Some fungi persist as dikaryons producing clones
    • Dikaryotic mycelia r Diploid
  10. Fruiting Bodies:
    • R dikaryotic
    • When mature, the 2 nuclei in cell walls will fuse
    • Produces zygotes (only diploid stage)
    • Undergo meiosis to produce haploid spores
    • Spores r disperse by wind, rain or animals
  11. Fungal Ecology:
    • Work with bacteria
    • Only certain bacteria and fungi can break down cellulose
    • Release minerals to soil and water
    • Some fungi r predators trapping tiny soil nematodes
  12. Fungal Pathogens:
    • Cause serious crop dzs like rust spores
    • Several human dzs:
    • Athlete's foot ringworm
    • Pneomocystis carinii pneumonia in AIDS
  13. Fungal Associations:
    • Beneficial associations w photosynthetic partners
    • Mycorhizzal fungi
    • Lichens
  14. Mycorhizzae
    • Association bwn hyphae of certain fungi and roots of most seed plants
    • More common in terrestrial plants
    • Plants receive increased supply of water and mineral nutrients
    • Fungi get organic food molecules from plants
    • 2 most common types:
    • Endomycorrhizae and ectomycorrhizae
  15. Endomycorrhizae
    • Fungi hyphae penetrate spaces bwn root cell walls and pm and grow along outer surgace of the pm
    • Arbuscular mycorrhizae (AM) form highly branched structures with high surface area
  16. Ectomycorrhizae
    • Coat root surface and grow bwn cells of roots
    • Some species of oak, beech, pine and spruce trees will not grow unless their ectomycorrhizal partners r also present.
  17. Lichens
    • Partnerships of fungi and photosyn green algae and or cyanobacteria
    • 3 major forms - crustose, foliose, fruticose
    • Photosyn partner provides organic food molecules and O2
    • Fungal partner provides CO2, water, and minerals
  18. Lichens reproduce:
    • sexually w fungal partner producing fruiting bodies and sexual spores
    • third can only reproduce asexually using soredia
  19. 4 Fungal Kingdoms
    • Chytridiomycota
    • Zygomycota
    • Ascomycota
    • Basidiomycota
  20. Chytridiomycota
    • Simplest fungi
    • Some r single, spherical cells that may produce hypae
    • Other r branched aseptate hyphae
    • Only produce flagellate cells for spores or gamete dispersal
    • Live in water or moist soil
  21. Zygomycota
    • Mycelium mostly aseptate hyphae
    • Produces asexual spores in sporangia
    • Named for zygospore produced sexually
    • begins w development of gametangia
    • Most r saprobes in soil
    • Some r parasites
    • Not monophyletic
  22. Ascomycota
    • Hyphae subdivided into cells by septa w simple pores
    • Unique sporangia called asci
    • Produce sexual spores called ascospores
    • Asci produced on fruiting bodies called ascocarps
    • Occur in terrestrail and aquatic habitat
  23. Basidiomycosta
    • Hyphae subdivided into cells by septa w complex spores
    • Most recently evolved grp of fungi along w Ascomycostya
    • Impt decomposers and mycorrihizal partners
    • Produce mushrooms, puffballs, stinkhorns, shelf fungi, rusts and smuts as fruiting bodies
    • Named for basidia that produce sexual spores called basidiospores
    • Fruiting bodies called basidiocarps
    • Clamp connections help distribute nuclei during cell division
    • Reproduce asexually by types of spores