Chapter31:Fungi

Fungi : sexual & asexual reproduction Eukaryotic Heterotrophic - feed by absorption Mostly multicellular except unicellular yeasts Chitin cell walls (polysaccharide) sexual & asexual reproduction

Fungal Structure Fungal body Cells Cell wall mycelium multiple nuclei thread-like cells (network of hyphae hyphae body filaments walls) septate (cross walls) coenocytic (no cross walls Cells multiple nuclei Cell wall chitin just like crab shells

Internal structure Eukaryotic cells long, thread-like cells chitin cell wall septum Eukaryotic cells long, thread-like cells filamentous incomplete divisions between cells septum multiple nuclei pore nuclei

Modes of Nutrition Heterotrophic secrete digestive enzymes feed by absorption parasites feeding on living creatures predators paralyzing prey Decomposer-saprobes breakdown dead remains plant cell fungal hypha plant cell membrane plant cell wall

Reproduction Asexual Sexual budding in yeast spores spread by wind joining of + & – haploid spores haploid spores

Fungi Diversity, I Phy: Chytridiomycota •aquatic fungi; chytrids •lineage closest to protists (flagella) Phy: Zygomycota •Rhizopus (food mold) •mycorrhizae: mutualistic with plant roots •zygosporangia: resistant structure (freezing and drying)

Fungi Diversity, II Phy.: Ascomycota •sac fungi • yeasts, truffles, morels, Sordaria •asci: sexual spores •conidia: asexual spores Phy.: Basidiomycota • club fungus •mushrooms, puffballs, shelf fungus, rusts •basidiocarps: produce sexual spores

Specialized Lifestyles, I Molds •only the asexual stage (asexual spores) •Penicillium (antibiotic, cheese) Yeasts •unicellular, asexual budding •Saccharomyces (bread, alcohol)

Specialized Lifestyles, II Lichens • symbiotic association held in a hyphae mesh •alga provides food, fungus provides physical environment •pioneer organisms •air pollution detection Mycorrhizae •root and fungi mutualism •found in 95% of vascular plants •exchange of organic minerals •increases absorptive surface of roots

Mycorrhizae Critical role in plant growth extends water absorption of roots without mycorrhizae with mycorrhizae Endomycorrhiza Ectomycorrhiza