Fungi
Laboratory
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Introduction
Molds, mushrooms, yeast, rusts and smuts are all members of a diverse group of haploid
eukaryotic organisms called fungi. Most members of this group are multicellular and
macroscopic, whereas some are single-celled and microscopic. Most fungal cells are enclosed
by a cell wall containing the polysaccharide chitin. Fungi begin their life cycle as spores that
divide rapidly to form threadlike structures called hyphae. These spores are single cells and
quite often are dispersed by the wind or air currents.
Hyphae grow in several directions and form a mass called mycelium. The hyphal strand of most
fungi is composed of individual cells separated by cross walls called septa. A few fungi,
including Rhizopus, have hyphae that lack septa and are a continuous mass of cytoplasm with
multiple nuclei. Hyphae with cross walls are termed septate hyphae and those lacking septa are
coenocytic. Most fungi reproduce by spores produced on specialized hyphae termed fruiting
bodies.
As saprophytes, the heterotrophic fungi release enzymes that break down organic compounds in
the environment which are subsequently absorbed. Most fungi live on dead and decaying
organic matter; thus, they play an important role in nutrient recycling and are known as
decomposers in food webs.
Some fungi are parasitic, especially on plants. Rusts, smuts and blights are common plant
diseases caused by fungi. Animals may also have fungal diseases, including athlete’s foot,
ringworm and vaginal yeast infections. Spores of certain fungi are known allergens while
penicillin (which is isolated from a fungus) is an important antibiotic.
Earlier classification of fungi was based mainly on sexual reproductive structures; however,
recent molecular data, such as comparative DNA and RNA sequencing, have also begun to play
a role in fungal classification. This lab will consider three phyla of Kingdom Fungi:
Kingdom Fungi
Phylum Zygomycota
Phylum Ascomycota
Phylum Basidiomycota
Study tip: You should be familiar with the characteristics of fungi and the terms in bold above.
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STATION 1: Phylum Zygomycota
Fungi belonging to this phylum are terrestrial and thrive in damp places. A representative
zygomycete, Rhizopus stolonifer (black bread mold), colonizes the moist interior of bread. In
asexual reproduction, aerial hyphae called sporangiophores terminate in spore-bearing
sporangia. The thousands of dark spores within the sporangium account for the common name
of black bread mold.
Sexual reproduction is triggered when there is scarcity of food. Two hyphae of different mating
strains (+/–) develop suspensors on which gametangia form. The gametangia fuse to form a
diploid zygospore with a rough outer coat. The zygospore is a dormant structure composed of a
zygote enclosed by a thick protective wall. Under appropriate conditions, zygospores undergo
meiosis to produce haploid spores that begin the next generation.
A. Using the model, label the life cycle of black bread mold, Rhizopus: hyphae, mycelium,
sporangiophore, sporangium, spores, suspensor, gametangia and zygospore.
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B. View demo slides of sporangia & zygospores : identify the sporangium, spores,
zygospores, coenocytic hyphae
Questions:
Where are spores produced? Are these spores haploid or diploid?
Which reproductive structure is produced sexually?
Rhizopus lacks cross walls in the hyphae. What term describes these hyphae?
What is the significance of the spores forming on the ends of the sporangiophores rather than
closer to the substrate?
Fill out the following chart:
Common name
Genus
Kingdom
Phylum
Black Bread Mold
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STATION 2: Phylum Ascomycota
Sac fungi
Peziza, also commonly known as a type of cup fungus, sexually reproduces by fusion of two
different strains (+/–) of hyphae. After fusion of the hyphae, the nuclei remain separate until
after the fruiting body, an ascocarp, is formed. The ascocarp contains long thin cells called asci
(ascus - singular). Within each ascus, meiosis followed by mitosis results in eight ascospores.
A. Label sexual reproductive structures of Peziza: mycelium, ascocarp, ascus, asospores
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B. View the demo slide of Peziza - observe all structures labeled above.
Questions:
Are the ascospores inside or outside of the ascus?
How many ascospores are in each ascus?
What structure is referenced when using the common name 'cup fungus' ?
Fill out the following chart:
Common name
Genus
Kingdom
Phylum
Peziza
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Lichens
A lichen is a symbiotic association between a fungus and a phototroph. The relationship occurs
between an ascomycete (or basidiomycete) and a green alga or cyanobacterium. In the past, it
had been assumed that this was a mutualistic partnership with the algae providing photosynthetic
products and the fungus providing protection, water and minerals. However, new data suggests
that lichen may be a form of controlled parasitism by the fungus.
Lichens typically grow on rocks or tree trunks. There are three commonly recognized lichen
growth forms. Crustose lichens are flat, foliose lichens are leaf-like and fruticose lichens are
branched and shrubby.
Crustose
Foliose
Fruticose
A. Using the specimens provided, compare/contrast crustose, foliose and fruticose forms.
B. View the lichen demo slide and compare with the following illustration:
Questions
In a lichen, which member is the autotroph?
Explain how lichens are able to grow in harsh environments like the artic tundra or on the
surface of a rock
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STATION 3: Phylum Basidiomycota
The common grey mushroom Coprinus, sexually reproduces by fusion of two different strains of
hyphae. After fusion of the hyphae, the haploid nuclei remain separate until after the fruiting
body, a basidiocarp, is formed. The basidiocarp consists of a cap, stalk (stipe) and gills. Spore
formation occurs within the gills on club-shaped basidia. As the basidiocarp open to expose the
gills, a ring of scar-tissue (annulus) is sometimes left behind on the stipe.
A. Label sexual reproductives structures of Coprinus: mycelium, basidiocarp, cap, stalk,
annulus, gills, basidium, basidiospores
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B. Examine a basidiocarp, identify the cap, stalk, gills and annulus.
C. View the demo slide of Coprinus - observe structures listed above.
Questions:
Are the basidiospores inside or outside of the basidium?
What happens to the basidiospores after they are released?
What cellular division process forms the four basidiospores each basidium produces?
Fill out the following chart:
Common name
Genus
Kingdom
Phylum
Common grey
mushroom
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Station Rotation and Setup for Fungi
**NOTE: Review General Characteristics & Taxonomy of Kingdom Fungi on Board
STATION 1
Phylum Zygomycota
general characteristics
review life cycle
bread mold model
sporangia demo slide
zygospore demo slide
STATION 1
30 minutes
STATION 2
Phylum Ascomycota
general characteristics
review life cycle
ascocarp specimens
Peziza demo slide
lichen types
lichen demo slide
STATION 2
30 minutes
STATION 3
Phylum Basidiomycota
general characteristics
review life cycle
basidiocarp specimens
Coprinus demo slide
Phylum Zygomycota
general characteristics
review life cycle
bread mold model
sporangia demo slide
zygospore demo slide
Phylum Ascomycota
general characteristics
review life cycle
ascocarp specimens
Peziza demo slide
lichen types
lichen demo slide
STATION 3
30 minutes
Phylum Basidiomycota
general characteristics
review life cycle
basidiocarp specimens
Coprinus demo slide
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