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Unformatted text preview: Lecture 3 Ch. 25 Fungi- monophyletic, sister group to animals, heterotrophic, eukaryotes, no plastids. Most fungi are molds Eukaryotes- cells contain membrane enclosed nuclei, mitochondria and other membranous organelles. Heterotrophs- cannot produce own organic material from a simple carbon source. Instead obtain preformed carbon molecules produced by other organisms. Do not ingest food- secrete digestive enzymes onto food source and absorb predigested food through their cell walls and plasma membranes Most decomposers- get nutrients from dead organic matter Require moisture to grow (moist habitats) Contains no plastids- no photosynthetic organelles Cell wall consists of complex carbohydrates including chitin (polymer that consists of subunits of nitrogen-containing sugar) Component of external skeleton, known as chitin (see last lecture)-[polymer that consists of subunits of nitrogen] of insects and arthropodsresistant to breakdown by most microorganisms Hundreds of fungal species are unicellularround or oval shaped bodies Yeast (unicellular) found in dirt, leaves, fruits, cured meats, on our bodies. Reproduction of Fungi Most fungi reproduce by means of Microscopic spores (non-mobile reproductive cells dispersed by wind, water, or animals) usually produced- aerial hyphae or fruiting structures. permits spores to be easily dispersed. Spores are produced in Fruiting Bodies. They contain a haploid nucleus- not normal Cycle of reproduction 1. the hyphae of two genetically equal mating types come together (cytoplasm and nuclei fuse= diploid cell, zygote a. three types of structures- i. gametangia- where gametes are formed ii. sportangia- structures in which spores are produced iii. conidiophores- specialized hypha that produce asexual spores called conidia. Two Fungal Groups- 1. Ascomycetes and 2. Basidiomycetes In these two, the hyphae fuse but the two different nuclei do not fuse immediately, rather they remain separate within the fungal cutoplasm....
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- Fall '08