Kingdom Fungi
Fungi What are they? Diverse group of eukaryotic organisms 100,000 to 1,000,000 species
Fungi Characteristics Kingdom includes Molds, mushrooms & yeasts Characteristically: Most are multicellular (yeasts are unicellular) Sessile heterotrophs secrete enzymes that digest their food outside their bodies then absorb nutrients into their cells Have cell walls made of chitin Use glycogen is energy storage molecule, not starch More closely related to animals than plants (why?)
Fungi Characteristics Found virtually everywhere in soil & water in light and dark Essential decomposers of most ecosystems Some are parasitic mostly on or in plants Some symbiotic many live in very close association with plant roots; called mycorrhizae, root fungi lichen are symbiotic fungus & algae; species specific
Fungi Characteristics Size ranges from unicellular to large honey mushroom in Oregon has a mycelial network over 2000 acres in size and is the largest organism on Earth (that is known) Most fungi are called obligate aerobes must have oxygen to survive Some are obligate anaerobes and some can deal with both anaerobic and aerobic conditions. ex. yeast intermediate, Chytridiomycota obligate anaerobes found in the gut (rumen) of cattle
Fungi Characteristics Two part body plan 1. Feeding hyphae: thread-like filaments that form a network called mycelium or a thallus (more generic than mycelium) lots of surface area to secrete digestive enzymes called exoenzymes small holes in the hyphae septa (the point where cells join) allow for increased nutrient uptake 2. Reproductive the mushroom (the fruiting body ); tightly packed mycelium; above ground to disperse spores
Fungus reproduction Reproduction in fungi can be perfect or imperfect perfect fungi can reproduce both asexually and sexually imperfect fungi can only reproduce asexually Asexual spores produced by mitosis release of spores dispersed (by wind, water or animals) that can develop into a multicellular haploid individual may also occur by fragmentation or budding conidia fungus producing asexual spores
Fungus reproduction Sexual 2 haploid mycelia of different mating types (+ and - ) release signaling molecules & grow toward each other & fuse cytoplasm fuses but not nuclei; for a while, cells are dikaryotic (!!) eventually nuclei fuse forming diploid stage (the fruiting body ); haploid spores are produced by meiosis these spores then form haploid mycelia
Fungi Classification The Kingdom Fungi is divided in to divisions these equated to phyla in classification Based primarily on reproductive strategies There are four divisions that reproduce sexually = Perfect Fungi 1. Chytridiomycota (chytrids) unique due to flagellated zoospores, some have both chitin and cellulose oldest and simplest true fungi 2. Zygomycota (conjugated fungi) bread molds, most are saprobes, produce resistant spores (zygospores) which may remain dormant for long periods of time
Fungi Classification The Kingdom Fungi is divided in to divisions these equated to phyla in classification Based primarily on reproductive strategies 3. Basidiomycota (club fungi) includes mushrooms, shelf fungus, smuts, toadstools sometimes called gill fungi due to the gill-like structures under the cap 4. Ascomycota (sac fungi) form an ascus (sac), includes yeasts and some disease causing fungi (fungal pneumonia) conidia are the asexual reproductive structures, and asci are the sexual reproductive structures Two divisions that reproduces only asexually = Imperfect Fungi Deuteromycota now recognized as the asexual variants of Ascomycota and Basidiomycota Glomeromycota - all live symbiotically with tree roots, forming arbuscular mycorrhizae (structures which take in nutrients and provide minerals)
Fungi Uses Ecological uses Decomposers crucial role in nutrient cycling May form symbiotic relationships with plants plants get water and minerals fungus gets glucose Environmentally Beneficial in mycorestoration have the ability to remove toxins from the environment Human uses food by themselves & in cheese & yogurt; yeast in bread & alcoholic drinks produce antibiotics soaps, dyes & food colorings TED Six Ways Fungi Can Save the World!
Next Time Plants!