Lecture 16 List the defining characteristics of Fungi 1 2 Describe the ecological and symbiotic roles of Fungi 3 Name and characterize each of the six groups of Fungi Secrete digestive enzymes outside of body Break down large food molecules Absorb breakdown products through plasma membrane Fungi are related to animals Opisthokonts Absorptive heterotrophy Chitin in cell walls Flagellated ancestor Developed from Unicellular protist with a flagella Absorptive heterotrophy Can also be Saprobes Parasites Mutualists Microsporidia Chytrids Fungi are made up of 6 major groups Not monophyletic Zygomycota zygospore fungi Not monophyletic Glomeromycota mycorrhizal fungi Ascomycota sac fungi Monophyletic Basidiomycota club fungi Monophyletic Unicellular fungi are called yeasts Aquatic moist Absorb nutrients through cell surfaces Yeasts are not monophyletic yeast refers to a lifestyle not a taxonomic group Includes Zygospore fungi zygomycota Sac fungi Ascomycota Club fungi basidiomycota Multicellular fungi are composed of hyphae Body of a multicellular fungus Composed of a mass of individual filaments hyphae Incomplete cross walls Subdivided cell like compartments in hyphae Mycelium Septum Septate Coenocytic Fungi that have septum Hyphae that lack septum Have hundreds of nuclei Dikaryotic N N Results from repeated nuclear divisions Fungi are absorptive heterotrophs External digestion Surface area to volume ratio Due to hyphae being close to environment Causes fungi to lose water rapidly in dry environments Absorption Fungi have cell walls with more than one nucleus Mitosis differences Production of haploid spores within structures called sporangia Production of haploid spores not enclosed in sporangia at the tips of hyphae are called conidia Cell division by unicellular fungi Fission Relatively equal division Budding Asymmetrical division Simple breakage of mycelium Plasmogamy Fusion of cytoplasm Karyogamy Fusion of nuclei No loss of nuclear envelope Most lack centrioles Fungi reproduce sexually or asexually Plasmogamy Karyogamy Mating types Genetically determined distinction Two fungi of the same mating type cannot reproduce Alternation of generations Conidia Not enclosed spores at tips of the hyphae Sporangia Enclosed spaces Fungi can be saprobes Global carbon cycle Carbon cycle would fail without fungi Nitrate ammonium but not N2 Obtain nitrogen from proteins products of protein breakdown Peat Formation leads to acidification of swamps Which drastically reduces fungal populations Permian extinction Fungi flourished Symbioses are partnerships that can be positive negative or in between Parasites that grow only on their specific living hosts Obligate Facultative Parasites that can attack living organisms but can also grow by themselves and in artificial environments Fungi can be pathogens parasites or predators Parasites Can produce haustonia Branching projections that push through cell walls into living plants cells Absorb nutrients from those cells Fungi may play a role in amphibian decline Batrachochytrum dendrobatidis Attacking amphibian populations Symbioses between fungi and bacteria cyanobacteria or green algae are called Lichens Most are Ascomycota 30 000 species Found in all sorts of exposed habitats Mycorrhizae are symbioses between plants and fungi Ectomycorrhizae Fungi wraps around the roots of plants Arbuscular mycorrhizae Fungi enter the root of plants and penetrates the cell wall of root cells Inside cell wall but outside plasma membrane Plants and colonization of land Mycorrhizar evolution was the single most important step in the colonization of the terrestrial environment by living things Microsporidia are unicellular parasites Lack mitochondria buthave mitostomes Derived from mitochondria Contain no DNA Unicellular fungi with walls that contain chitin Obligate parasites Can infect mammals and even humans Penetrate host with polar tube Sporoplasm Replicates within host cell and produces new infective spores Chytrids have flagella Once classified as protists Aquatic Environment where fungi first evolved Flagellated gametes Parasitic saprobic Many live in freshwater or moist soil but some are marine Coenocytic but not dikaryon Zygospore fungi produce zygotes Haploid for most of their life Reproduce largely asexually Glomeromycota are asexual plant symbionts Obligate symbionts Asexual reproduction Sister group to dikarya Ascomycota produce sac like fruiting bodies Sexual and asexual reproduction Dikaryon Asci Include yeast penicillin truffles Sacs that contain sexually produced ascospores Basidiomycota have dikaryotic mushrooms Saprobic Basidiomata Fruiting structures N N Diploid momentarily Basidium Sexual reproductive structure