Mader: Biology 8 th Ed. Characteristics of the Fungi Kingdom Fungi contains the fungi. – Mostly multicellular eukaryotes that share a common mode of nutrition. Heterotrophic Cells release digestive enzymes and then absorb resultant nutrient molecules. Some are parasitic. Several have mutualistic relationship.
Mader: Biology 8 th Ed. Structure of Fungi Yeasts are best known example of unicellular fungi. – Body (thallus) of most fungi is multicellular mycelium. Network of hyphae give the mycelium a large surface area per unit volume.
Mader: Biology 8 th Ed. Structure of Fungi Fungal cells are quite different from plant cells. – Lack chloroplasts and have a cell wall containing chitin and not cellulose. – Energy reserve is glycogen, not starch. Nonmotile – Septate fungi have cross walls in their hyphae. – Nonseptate fungi are multinucleated.
Mader: Biology 8 th Ed. Reproduction of Fungi Both sexual and asexual reproduction occur. Fungal sexual reproduction involves three stages: – Haploid Hyphae – Dikaryotic Stage – Diploid Zygote
Mader: Biology 8 th Ed. Reproduction of Fungi During sexual reproduction, hyphae from two different mating types fuse. – Hyphae that contains paired haploid nuclei is said to be dikaryotic. – Fungal spores germinate directly into haploid hyphae without embryological development. Asexual reproduction usually involves the production of spores. – Unicellular yeasts reproduce by budding.
Mader: Biology 8 th Ed. Evolution of Fungi Has been suggested fungi evolved from red algae because both fungi and red algae lack flagella in all stages of the life cycle. – Zygospore Fungi (phylum Zygomycota) are mainly saprotrophs living off animal and plant remains. Produce spores with sporangia. Name refers to the zygospore seen during sexual reproduction.
Mader: Biology 8 th Ed. Sac Fungi Most sac fungi (phylum Ascomycota) are saprotrophs that digest resistant materials containing cellulose, lignin, or collagen. – Most are composed of septate hyphae. – Ascus refers to the fingerlike sac that develops during sexual reproduction. Asci usually surrounded and protected by sterile hyphae within an asocarp. – Asexual reproduction involves production of conidiospores.
Mader: Biology 8 th Ed. Yeasts Term yeasts is generally applied to unicellular fungi. – Many are ascomycetes. – Budding is common form of asexual reproduction. – Sexual reproduction results in the formation of asci and ascospores. – When some yeast ferment, they produce ethanol and carbon dioxide.
Mader: Biology 8 th Ed. Club Fungi Club fungi (phylum Basidomycota) include mushrooms and bracket fungi. – These are fruiting bodies called basidiocarps. Contain basidia, club-shaped structures that produce basidiospores. – Usually reproduce sexually.
Mader: Biology 8 th Ed. Smuts and Rusts Smuts and rusts are club fungi that parasitize cereal crops. – Great economic importance because of annual crop losses. Do not form basidiocarps. Life cycle often requires two different plant hosts to complete the cycle.
Mader: Biology 8 th Ed. Imperfect Fungi Imperfect fungi (phylum Deuteromycota) always reproduce asexually by forming conidiospores. – Produced at tips of modified aerial hyphae. – Known as imperfect in the sense that a sexual stage has not yet been observed. Penicillium - Penicillin Aspergillus - Soy sauce Candida albicans- Yeast infections
Mader: Biology 8 th Ed. Symbiotic Relationships Lichens – Association between a fungus and a cyanobacterium or green alga. Specialized fungal hyphae penetrate photosynthetic cells and transfer nutrients directly to the fungus. Can live in areas of extreme conditions and contribute to soil formation.
Mader: Biology 8 th Ed. Mycorrhizas Mycorrhizas are mutualistic relationships between soil fungi and the roots of most plants. – Help plants acquire mineral nutrients. Give plant greater absorptive surface.