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Kingdom Fungi Finding the Fungus Among Us Characteristics of Fungi • • • • • Eukaryotic Most are Multicellular Filamentous body plan Heterotrophic by Absorption Produce spores by sexual and asexual reproduction • Haploid for part or most of life cycle • Cell wall made of chitin • No movement: change location by growth of body or dispersion of spores The Filamentous Body of a Fungus (a) Mycelium (c) Hyphal Cells (cutaway) Cytoplasm (b) Individual Hyphae Haploid Nuclei Septum Pore Cell Walls Body Plan of Fungi • Mycelium = network of filaments • Hypha = individual filament (plural = hyphae) • Septum = partition dividing cells, has pore for distribution of nutrients • Reproductive structure extends from main body, produces spores Fungal Nutrition • Heterotropic by absorption – secrete digestive enzymes – digest macromolecules outside the body – absorb digested nutrients • Three nutritional modes – Saprophytic = digestion of dead organisms – Parasitic = digestion of live organisms, causing disease – Mutualistic = beneficial relationship for two independent organisms Saprophytes Parasites Lichen: Mutualism Between Alga and Fungus Algal Layer Fungal Hyphae Attachment Structure Mycorrhizae: Mutualism Between Fungus and Plant Roots Applying Your Knowledge 1. Parasitic 2. Saprophtyic 3. Mutualistic Which mode of nutrition A. Provides a benefit for the fungus and its symbiotic partner? B. Is shown by athlete’s foot fungus? C. Involves digestion of dead organisms? Sexual Reproduction • Hypha from mycelia of opposite mating types fuse • Fusion of two haploid nuclei forms diploid zygote • Zygote produces haploid spores by meiosis • Each spore germinates to produce a haploid mycelium Chythrid Fungi • Flagellated, swimming spores require water for dispersal • Ancestral group, gave rise to modern fungi Forming Male Gametes Forming Female Gametes Zygote Fungi • Live in soil and on decaying plant matter • Zygosporangia = reproductive structures producing haploid spores Sac Fungi • Ascus = sac that surrounds haploid ascospores Club Fungi • Basidium = club-shaped reproductive structure that produces basidiospores Club Fungus Life Cycle Haploid Nuclei Fusion forms diploid zygote. Basidia on gills Basidiospores (haploid) Haploid 1n Diploid 2n Mushroom gills bear reproductive basidia. Club Fungus Life Cycle Basidiospores (haploid) Hyphae aggregate to form mushroom Basidia on gills “+” Mating Strain Basidiospores germinate forming hyphae (haploid). + Haploid 1n Diploid 2n - “-” Mating Strain Hyphae fuse, but haploid nuclei remain separate in binucleate cells Imperfect Fungi • Sexual reproduction has not been observed Applying Your Knowledge 1. 2. 3. 4. 5. Chytrids Zygote Fungi Sac Fungi Club Fungi Imperfect Fungi Which group of fungi A. Encloses haploid spores within an ascus? B. Has flagellated gametes? C. Has an umbrella-shaped reproductive structure called a basidium? D. Has not shown sexual reproduction? Applying Your Knowledge 1. 2. 3. 4. 5. Chytrids Zygote Fungi Sac Fungi Club Fungi Imperfect Fungi Which group of fungi A. Are found on as a topping your mushroom pizza? B. Caused the pizza dough to rise? C. Make up the fuzzy structure on the twoweek old loaf of bread in your cupboard? Applying Your Knowledge 1. 2. 3. 4. 5. Prokaryotes Protists Fungi Plantae Animalia Which kingdom/domain A. Has organisms that are heterotrophic by ingestion? B. Has cell walls made of chitin? C. Reproduces by binary fission?
