BIOL 1108 Edition 1nd Lecture 9 Outline of Last Lecture I Learning Objectives II In The News III Functions of Cilia IV Symbiogenesis V Origin of Mitochondria VI Hydrogen Hypothesis VII Mitochondrial Metabolism VIII Ring of Life IX Stromatolites Outline of Current Lecture I Learning Objectives II Portistan Diversity III The Five Kingdom System IV Characteristics of Fungi V Fungal Body VI Saprotrophic Nutrition VII Roles of Fungi These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute VIII Chytrids IX Microsporidia Current Lecture I II III IV Learning Objectives What distinguishes fungi from other eukaryotes What distinguishes animals from other eukaryotes Why were fungi traditionally studied along with plants in botany departments What are some of the ecological roles played by fungi What is the evolutionary history of fungi Of animals What links the two together Portistan Diversity Unikont a single clilium per cell Bikont two cilia or multiples of two per cell Opisthokonts o Opistho behind kont cilium o Flattened mitochondrial cristae o Single posterior cilium o Part of the Animalia and fungi kingdoms o Example sperm In the 15th century people thought sperm contained a little human in it homunculus that developed into a baby The idea that fungi and animals all share a common ancestor is a relatively recent idea but it is exceedingly well supported by morphological biochemical and genetic evidence The Five Kingdom System Proposed in 1969 by Robert Whittaker was the first significant change in the tree of life since Haeckel s three kingdom plus Monera scheme in 1865 Included Monera Protists Plants Animals and Fungi Whittaker s erection of the fungi as a distinct clade was based mainly upon differences in nutrition his Plantae were mostly multicellular autotrophs his Animalia multicellular heterotrophs and his Fungi multicellular saprotrophs Before 1969 fungi were considered to be part of the Plant Kingdom because like plants fungi do not move around Characteristics of Fungi Absorptive heterotrophs n organism which secretes enzymes externally into its environment to digest organic materials which are then absorbed Cell walls made of chitin V VI VII o Chitin is found throughout the fungi as well as in many invertebrates exoskeletons of arthropods as well as some of the hard parts of molluscs such as the beaks of squid and octopus o Chitin is a long chain polymer of a N acetylglucosamine o The structure of chitin is comparable to the polysaccharide cellulose forming crystalline nanofibrils or whiskers In terms of function it may be compared to the protein keratin No flagella most o Instead fungi have hyphae The function of hyphae is somewhat analogous to the roots of plants in that they both form branching structures have apical terminal growth and play a role in nutrient and water uptake Characteristics include Thread of cells that are one cell thick to increase high surface area to volume ratio Other functions are to absorb water ions nutrients gas exchange and waste disposal Immobile Fungal Body The Honey Mushrooms of Malheur National Forest in the Blue Mountains of eastern Oregon were determined to be genetic clones connected by a single mycelial network This most recent find was estimated to cover over 2 200 acres 890 hectares and be at least 2 400 years old The fungal body includes o Mycelium is the vegetative part of a fungus consisting of a mass of branching thread like hyphae o Loosely woven mat of hyphae o Feeding structure Reproductive structures o Make spores either by mitosis or meiosis o Some are called fruiting bodies Saprotrophic Nutrition Is a process of chemoheterotrophic extracellular digestion involved in the processing of dead or decayed organic matter It occurs in saprotrophs or heterotrophs and is most often associated with fungi and soil bacteria o Heterotrophic by absorption Fungi get carbon from organic sources Hyphal tips release enzymes Enzymatic breakdown of substrate Products diffuse back into hyphae Roles of Fungi VIII IX Ecological roles that fungi play include being o Decomposers saprobes o Pathogens Predators o Partners in primary production The algal partner in the lichen symbiosis is usually a type of green alga but in some species it is a cyanobacterium that is the source of photosynthesis A mycorrhiza is a symbiotic generally mutualistic but occasionally weakly pathogenic association between a fungus and the roots of a vascular plant Plants grown in the absence of mycorrhizae have poorly developed root masses and reduced growth rates Mycorrhizae also play an important role in the establishment of epiphytic plants such as orchids and bromeliads o Parasites Examples corn smut on corn and ergots on rye Cordyceps Strains of Cordyceps appear to be very host specific which has the potential of using Cordyceps as a means of biological control for certain pest arthropods Chytrids Sporangia release motile zoospores which swim through the water until they reach a suitable substrate Then they settle down and form a sporangium Chytridiosis is caused by Batrachochytrium kills a lot of amphibians Possible explanations for its rapid spread include the global trade in amphibians and ironically the movement of herpetologists who were trying to document amphibian die offs Microsporidia Extend their polar tube into a host cell and the cell s nucleus and cytoplasm migrates into the host cell Once safely inside the parasite begins to replicate The traces of Nosema can best be seen in the spring when bees are old and weak after winter Individuals with weakened immune systems are prone to a variety of fungal and protistan infections that are generally much less severe in people who have a healthy immune response to these pathogens Microsporidiosis o Symptoms general occur in people with immune deficiency o Cause of bowel lung kidney brain sinus and eye disease in people with AIDS and other conditions that are caused by immune deficiencies o Intestinal symptoms that are caused by microsporidia infection include wasting chronic diarrhea and gallbladder disease