chapter 21 mrs. lalone. kingdom fungi mycologists study fungus! eukaryotic organisms ex: mushrooms,...
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Kingdom FungiChapter 21
Mrs. LaLone
Kingdom FungiMycologists study fungus!Eukaryotic Organisms
Ex: Mushrooms, yeasts, molds70,000+ species of FungusMostly TerrestrialForm spores at some stage of lifecycleHave a Cell Wall
Composed of chitin – Nitrogen based polysaccharide
Resistant to breakdown by microorganismsMore resistant than cellulose
NutritionAll are Heterotrophic
Most are saprophytic – feed on the remains of dead organisms “decomposers” Fungi secrete enzymes that initiate digestion
outside the hypha Then absorb nutrients through the plasma
membranes of their cellsSome are parasitic – obtain nutrients from
living organisms; ex: plant pests
ClimateGrow best in moist environments
Produce spores in dry environments (resting stage)
Optimum pH is slilghtly acidic ~5.6 Range from 2-9
Wide temperature range
Body PlansUnicellular: YeastsMulticellullar: filamentous molds
MildewsWheat rustCorn smutMushroomsOther fungi
Body PlansFilamentous molds
Mold – consists of long, branched threads (filaments) “hyphae” Form a tangled mass/tissue “mycellium” Some coenocytic – large, multinucleated mass Some have septa – cross-walls with pores
Dikaryotic – contain 2 genetically distinct nuclei Monokaryotic – contain only one nucleus See Figure 21-1
Fig. 21-1, p. 407
FungusHave 2 distinct stages
Vegetative stage Often goes unnoticed
Conspicuous Reproductive stage The familiar form that people notice
Mushrooms, puffballs, bracket fungi
ReproductionSexual
Fruiting bodies (the familiar forms of fungi) Ex: mushroom top
Plasmogamy 2 different hyphae come together and cytoplasm
fuses 2 haploid nuclei fuse (karyogamy) Results in diploid zygote nucleus Meiosis occurs; producing haploid spores
ReproductionAsexual
FissionBuddingSpore Formation
Spores – nonmotile reproductive cells (wind & animals)
Produce on aerial hyphae Allows air currents to disperse cells
ClassificationBased on:
Characteristics of sexual sporesCharacteristics of fruiting bodiesDNA & RNA sequences
Kingdom Fungi5 Phyla
Phylum Chytridiomycota (Chytrids)Phylum Zygomycota (Sporangium Fungi)Phylum Glomeromycota (Mycorrhizae)Phylum Ascomycota (Sac Fungi)Phylum Basidiomycota (Club Fungi)
Phylum Chitridiomycota: ChytridsFungus that produce flagellated cells at some
stage in its lifeInhabit ponds, damp soil, & some in saltwaterMost are decomposers, some cause diseases
in plants and animalsMost unicellular or few cells that compose a
thallus a simple body that lacks roots, stems, or leaves &
rhizoids anchor/root-like
Phylum ZygomycotaBlack Bread MoldProduce zygosporesCoenocytic hyphaeSee figure 21-6
Fig. 21-6, p. 410
Zygomycetes
Phylum GlomeromycotaMycorrhizae – “Fungus Roots” a symbiotic
association between fungus and plant rootThe roots supply the fungus with sugars,
aminoacids, and other organic substancesThe mycorrhizal fungus benefits the plant by
extending the reach of its roots helps plant take in more water and minerals
Coenocytic (no septa) hyphae Asexual – blastospore (multinucleate
spores)
Fig. 21-8, p. 412
Glomeromycetes
Fig. 21-15a, p. 419
Fig. 21-15b, p. 419
Phylum AscomycotaSac Fungi
Their spores are produced in little sacs called asciHyphae usually have perforated septa
Cytoplasm and nuclei can move from one cell to another
Examples: Powdery mildews (cause food to spoil)Cup fungiEdible morels and trufflesYeastsDiseases caused: Dutch elm disease, chestnut blight, ergot
disease on rye, mildew on fruitsNonmotileSexual – ascospores (ascocarp=fruiting body)Asexual – spores called conidia
Fig. 21-11a, p. 415
Ascomycetes
Phylum Basidomycota“Club Fungi”Mushrooms, bracket fungi, puffballsParasites – wheat rust & corn smutDevelop basidium & basidiosporesMasses of hyphae form buttons
Each button forms a mushroom = stalk + cap Called a “basidiocarp” Have gills on lower surface of cap
Fig. 21-12, p. 416
Fig. 21-13, p. 417
Phylum Basidomycota
Ecological ImportanceDecomposeRelease CO2 to PlantsWithout fungus, minerals would be locked up
in dead organic matter; life would cease
Ecological ImportanceSymbiotic relationships
Animals (ex: cattle) cannot digest cellulose and lignin by themselves Fungi in gut do this
Mycorrhizae and plant rootsLichens – symbiotic relationships between
fungus + photosynthetic organism Ex: green alga or a cyanobacterium + ascomycete
fungus
Fig. 21-16, p. 420
Lichens
Lichens3 Growth Forms
Crustose – flat and grow tightly attached to rock
Foliose – Flat, leaflike lobes, not as tightly attached
Fruticose – Grow erect, branched/shrublike
LichensTolerate extremes of temperature and
moistureDo not grow in heavily polluted cities
Fungi are used to produceBeer – yeasts ferment grain (barley)Bread – yeast produce carbondioxide, and alcohol
(evaporates during baking)Cheeses Wine – yeast ferments fruit sugars to become ethyl alchololPenicillin – produced by a mold200 species of edible mushrooms70 poisonous
No easy way to distinguishSome have similar chemicals as LSD – trancelike state and
colorful visionsUsed for insecticidesPrevent spreading of malaria
Fungal DiseasesSuperfical infections (only infect skin, hair, or nails)
RingwormAthlete’s footJock itch
Candidiasis – yeast infection of mouth, throat, and vaginaOpportunistic fungi (occur when immune system is
compromised)Histoplasmosis – infection of lungs caused by inhaling
the spores of a fungus abundant in bird droppingsLiver damage and cancer
Caused by mycotoxins commonly grow on peanuts, pecans, corn, and other grains