Chapter 21
Mrs. LaLone
Kingdom Fungi
 Mycologists study fungus!
 Eukaryotic Organisms
 Ex: Mushrooms, yeasts, molds
 70,000+ species of Fungus
 Mostly Terrestrial
 Form spores at some stage of lifecycle
 Have a Cell Wall
 Composed of chitin – Nitrogen based polysaccharide
 Resistant to breakdown by microorganisms
 More resistant than cellulose
Nutrition
 All 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 cells
 Some are parasitic – obtain nutrients from living
organisms; ex: plant pests
Climate
 Grow 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 Plans
 Unicellular: Yeasts
 Multicellullar: filamentous molds
 Mildews
 Wheat rust
 Corn smut
 Mushrooms
 Other fungi
Body Plans
 Filamentous 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
Fungus
 Have 2 distinct stages
 Vegetative stage

Often goes unnoticed
 Conspicuous Reproductive stage

The familiar form that people notice
 Mushrooms, puffballs, bracket fungi
Reproduction
 Sexual
 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
Reproduction
 Asexual
 Fission
 Budding
 Spore Formation



Spores – nonmotile reproductive cells (wind & animals)
Produce on aerial hyphae
Allows air currents to disperse cells
Classification
 Based on:
 Characteristics of sexual spores
 Characteristics of fruiting bodies
 DNA & RNA sequences
Kingdom Fungi
 5 Phyla
 Phylum Chytridiomycota (Chytrids)
 Phylum Zygomycota (Sporangium Fungi)
 Phylum Glomeromycota (Mycorrhizae)
 Phylum Ascomycota (Sac Fungi)
 Phylum Basidiomycota (Club Fungi)
Phylum Chitridiomycota: Chytrids
 Fungus that produce flagellated cells at some stage in
its life
 Inhabit ponds, damp soil, & some in saltwater
 Most are decomposers, some cause diseases in plants
and animals
 Most unicellular or few cells that compose a
 thallus a simple body that lacks roots, stems, or leaves
&
 rhizoids anchor/root-like
Phylum Zygomycota
 Black Bread Mold
 Produce zygospores
 Coenocytic hyphae
 See figure 21-6
Zygomycetes
Fig. 21-6, p. 410
Phylum Glomeromycota
 Mycorrhizae – “Fungus Roots” a symbiotic association
between fungus and plant root
 The roots supply the fungus with sugars, aminoacids,
and other organic substances
 The 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)
Glomeromycetes
Fig. 21-8, p. 412
Fig. 21-15a, p. 419
Fig. 21-15b, p. 419
Phylum Ascomycota
 Sac Fungi
 Their spores are produced in little sacs called asci
 Hyphae usually have perforated septa

Cytoplasm and nuclei can move from one cell to another
 Examples:
 Powdery mildews (cause food to spoil)
 Cup fungi
 Edible morels and truffles
 Yeasts
 Diseases caused: Dutch elm disease, chestnut blight, ergot disease
on rye, mildew on fruits
 Nonmotile
 Sexual – ascospores (ascocarp=fruiting body)
 Asexual – spores called conidia
Ascomycetes
Fig. 21-11a, p. 415
Phylum Basidomycota
 “Club Fungi”
 Mushrooms, bracket fungi, puffballs
 Parasites – wheat rust & corn smut
 Develop basidium & basidiospores
 Masses 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 Importance
 Decompose
 Release CO2 to Plants
 Without fungus, minerals would be locked up in dead
organic matter; life would cease
Ecological Importance
 Symbiotic relationships
 Animals (ex: cattle) cannot digest cellulose and lignin by
themselves

Fungi in gut do this
 Mycorrhizae and plant roots
 Lichens – symbiotic relationships between fungus +
photosynthetic organism

Ex: green alga or a cyanobacterium + ascomycete fungus
Lichens
Fig. 21-16, p. 420
Lichens
 3 Growth Forms
 Crustose – flat and grow tightly attached to rock
 Foliose – Flat, leaflike lobes, not as tightly attached
 Fruticose – Grow erect, branched/shrublike
Lichens
 Tolerate extremes of temperature and moisture
 Do not grow in heavily polluted cities
Fungi are used to produce
 Beer – yeasts ferment grain (barley)
 Bread – yeast produce carbondioxide, and alcohol (evaporates





during baking)
Cheeses
Wine – yeast ferments fruit sugars to become ethyl alcholol
Penicillin – produced by a mold
200 species of edible mushrooms
70 poisonous
 No easy way to distinguish
 Some have similar chemicals as LSD – trancelike state and
colorful visions
 Used for insecticides
 Prevent spreading of malaria
Fungal Diseases
 Superfical infections (only infect skin, hair, or nails)
 Ringworm
 Athlete’s foot
 Jock itch
 Candidiasis – yeast infection of mouth, throat, and vagina
 Opportunistic fungi (occur when immune system is
compromised)
 Histoplasmosis – infection of lungs caused by inhaling the
spores of a fungus abundant in bird droppings
 Liver damage and cancer
 Caused by mycotoxins commonly grow on peanuts, pecans,
corn, and other grains