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Unformatted text preview: Chapter 30 Fungi: Recyclers, Pathogens, and Plant Partners How Do Fungi Thrive in Virtually Every Environment? Fungi and animals are descended from a common ancestor: A unicellular eukaryote with a flagellum Synapomorphies (common characteristics) that distinguish the fungi: Absorptive heterotrophy Chitin in cell walls The kingdom Fungi consists of five phyla: Chytridiomycota Zygomycota * Glomeromycota Ascomycota * Basidiomycota * * focus on in lab Phyla are primarily distinguished by their methods and structures of reproduction General Biology of the Fungi Fungi live by absorptive nutrition secrete digestive enzymes to break down large food molecules absorb breakdown products Variety of lifestyles: Most are saprobes absorb nutrients from dead matter Many others are parasites A few have mutually beneficial ( mutualistic ) relationships with other organisms Chitin is used in cell walls in fungi. chitin production is a shared derived trait for fungi, choanoflagellates, and animals Provides evidence that all fungi are more closely related to animals than to plants Unicellular forms are found in all of the fungal phyla. those of the Zygomycota, Ascomycota, and Basidiomycota are called yeasts yeasts may reproduce by budding, fission, or sexual means The mycelium (plural, mycelia) is the vegetative body of multicellular fungi. mycelia are composed of threadlike hyphae Some hyphae have septa (incomplete cross-walls) that separate hyphae into cell- like compartments pores in septa allow free movement of materials, organelles, sometimes even nuclei some hyphae are coenocytic they lack internal septa Hyphae may be widely dispersed to forage for nutrients or clumped together to exploit a rich nutrient source growing up to 1 km/day Hyphae sometimes become reorganized into a fruiting (reproductive) structure, e.g. mushroom or this morel Some parasitic fungi may have modified hyphae that take up nutrients. invade wounds or stoma on plants and grow mycelium throughout the plant some hyphae produce haustoria , branches that push into cells to absorb nutrients Mycelia have very high surface area-to-volume ratio for better absorption . Hyphae (except in fruiting structures) are very close to their environmental food source But water loss is high so are usually found in moist habitats Fungi are tolerant of highly hypertonic environments....
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This note was uploaded on 12/03/2010 for the course BSC 2010 taught by Professor Bowes during the Spring '08 term at University of Florida.
- Spring '08