The Fungi
Chapter 23
Mader: Biology 8 th Ed.

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Outline
Characteristics
Structure
Reproduction
Evolution
Sac Fungi
Yeasts
Club Fungi
Smuts and Rusts
Imperfect Fungi
Symbiotic Relationships
Mader: Biology 8 th Ed.

Characteristics of the Fungi
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Kingdom Fungi contains the fungi.
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Mostly multicellular eukaryotes that share a common mode of nutrition.
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Heterotrophic
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Cells release digestive enzymes and then absorb resultant nutrient molecules.
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Some are parasitic.
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Several have mutualistic relationship.
Mader: Biology 8 th Ed.

Structure of Fungi
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Yeasts are best known example of unicellular fungi.
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Body ( thallus ) of most fungi is multicellular mycelium .
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Network of hyphae give the mycelium a large surface area per unit volume.
Mader: Biology 8 th Ed.

Mycelium of Fungi
Mader: Biology 8 th Ed.

Structure of Fungi
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Fungal cells are quite different from plant cells.
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Lack chloroplasts and have a cell wall containing chitin and not cellulose.
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Energy reserve is glycogen, not starch.
Nonmotile
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Septate fungi have cross walls in their hyphae.
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Nonseptate fungi are multinucleated.
Mader: Biology 8 th Ed.

Reproduction of Fungi
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Both sexual and asexual reproduction occur.
Fungal sexual reproduction involves three stages:
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Haploid Hyphae
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Dikaryotic Stage
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Diploid Zygote
Mader: Biology 8 th Ed.

Reproduction of Fungi
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During sexual reproduction , hyphae from two different mating types fuse.
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Hyphae that contains paired haploid nuclei is said to be dikaryotic .
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Fungal spores germinate directly into haploid hyphae without embryological development.
Asexual reproduction usually involves the production of spores .
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Unicellular yeasts reproduce by budding .
Mader: Biology 8 th Ed.

Evolution of Fungi
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Has been suggested fungi evolved from red algae because both fungi and red algae lack flagella in all stages of the life cycle.
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Zygospore Fungi
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(phylum Zygomycota) are mainly saprotrophs living off animal and plant remains.
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Produce spores with sporangia.
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Name refers to the zygospore seen during sexual reproduction.
Mader: Biology 8 th Ed.

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Sac Fungi
Most sac fungi (phylum Ascomycota) are saprotrophs that digest resistant materials containing cellulose, lignin, or collagen.
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Most are composed of septate hyphae.
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Ascus refers to the fingerlike sac that develops during sexual reproduction.
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Asci usually surrounded and protected by sterile hyphae within an asocarp .
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Asexual reproduction involves production of conidiospores .
Mader: Biology 8 th Ed.

Yeasts
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Term yeasts is generally applied to unicellular fungi.
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Many are ascomycetes.
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Budding is common form of asexual reproduction.
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Sexual reproduction results in the formation of asci and ascospores.
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When some yeast ferment, they produce ethanol and carbon dioxide.
Mader: Biology 8 th Ed.

Yeast Cells
Mader: Biology 8 th Ed.

Club Fungi
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Club fungi (phylum Basidomycota) include mushrooms and bracket fungi.
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These are fruiting bodies called basidiocarps .
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Contain basidia , club-shaped structures that produce basidiospores.
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Usually reproduce sexually.
Mader: Biology 8 th Ed.

Club Fungi
Mader: Biology 8 th Ed.

Smuts and Rusts
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Smuts and rusts are club fungi that parasitize cereal crops.
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Great economic importance because of annual crop losses.
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Do not form basidiocarps.
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Life cycle often requires two different plant hosts to complete the cycle.
Mader: Biology 8 th Ed.

Smuts and Rusts
Mader: Biology 8 th Ed.

Imperfect Fungi
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Imperfect fungi (phylum Deuteromycota) always reproduce asexually by forming conidiospores.
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Produced at tips of modified aerial hyphae.
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Known as imperfect in the sense that a sexual stage has not yet been observed.
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Penicillium - Penicillin
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Aspergillus - Soy sauce
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Candida albicans - Yeast infections
Mader: Biology 8 th Ed.

Penicillium
Mader: Biology 8 th Ed.

Symbiotic Relationships
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Lichens
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Association between a fungus and a cyanobacterium or green alga.
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Specialized fungal hyphae penetrate photosynthetic cells and transfer nutrients directly to the fungus.
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Can live in areas of extreme conditions and contribute to soil formation.
Mader: Biology 8 th Ed.

Lichen Morphology
Mader: Biology 8 th Ed.

Mycorrhizas
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Mycorrhizas are mutualistic relationships between soil fungi and the roots of most plants.
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Help plants acquire mineral nutrients.
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Give plant greater absorptive surface.
Mader: Biology 8 th Ed.

•
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•
•
•
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•
•
•
•
Review
Characteristics
Structure
Reproduction
Evolution
Sac Fungi
Yeasts
Club Fungi
Smuts and Rusts
Imperfect Fungi
Symbiotic Relationships
Mader: Biology 8 th Ed.

Mader: Biology 8 th Ed.