FUNGI Terms to know Lignin Found in wood A complex hydrophobic polyphenolic polymer in plant cell walls that crosslinks other wall polymers strengthening the walls Chitin a fibrous substance consisting of polysaccharides and forming the major constituent in the exoskeleton of arthropods and the cell walls of fungi Requires nitrogen Heterokaryon A multinucleated cell that contains genetically different nuclei Mitospore A haploid or diploid spore produced by mitosis A sexual reproduction Ascus a sac typically cylindrical in shape in which the spores of ascomycete fungi develop Meiospore The spore produced by meiosis such as the precursor cells of gametophytes of angiosperms and gymnosperms Karyogamy is the final step in the process of fusing together two haploid eukaryotic cells and refers specifically to the fusion of the two nuclei Nuclear fusion goes from 1N to 2N Plasmogamy is a stage in the sexual reproduction of fungi in which the cytoplasm of two parent cells usually from the mycelia fuses together without the fusion of nuclei effectively bringing two haploid nuclei close together in the same cell Joining of cytoplasm rom two mycelia Lichen is a composite organism that arises from algae or cyanobacteria or both living among filaments of a fungus in a symbiotic relationship Mycorrhizae a fungus that grows in association with the roots of a plant in a symbiotic or mildly pathogenic relationship Pilobolus is a genus of fungi that commonly grows on herbivore dung POOP FUNGI Rhizopus is a genus of common saprophytic fungi on plants and specialized parasites on animals extracellular digestion Secreting enzymes onto food to digest the organism then returns when the food is broken down small enough to be taken up by passive diffusion or phagocytosis ascocarp or ascoma plural ascomata is the fruiting body sporocarp of an ascomycete phylum fungus It consists of very tightly interwoven hyphae and may contain millions of asci each of which typically contains four to eight ascospores Ubiquity is the state of being everywhere all the time Questions to think about 1 Describe how fungi feed what is absorptive heteromorphy exoenzymes Heterotrophs that absorb nutrients outside of their bodies They secrete enzymes outside of their body to digest their food and reabsorb the nutrients Exodigestion Exoenzymes The secreted enzymes used to digest their nutrients Absorptive heteromorphy is the process fungi use to get their food 1 What is a heterokaryotic dikaryotic cell use notation and a sketch A multinucleated cell that contains genetically different nuclei a how would you describe each nucleus in a dikaryotic cell Dikaryotic cells are cells with two nuclei b what is the sister group to the fungi Animals 3 Name two polymers that fungi can degrade that most bacteria plants and animals cannot where they occur and discuss the ecological significance of the process Cellulose found plant cell wall and Lignin found in seed coats Rotting wood The ecological significance of this process is that they degrade waste such as dead plants Cellulose primary growth Height Lignan secondary growth Girth 4 Discuss the differences between a saprobe a parasite and a mutualistic organism define these terms Saparobe which live on dead material dead bodies dead plant material dead animal materials Most Fungi are saparobes Most Fungi require the plant or whatever to be dead before it can flourish They are decomposers Parasite An organism that consumes parts of an organism much larger than itself Parasites sometimes But not always kill their host Mutualistic An organism that forms a relationship with another that is mutually beneficial a which of these causes dry rot of Nevada homes A Saprobe Most Fungi are Saprobe because of its decomposing abilities 5 What is the advantage to a species of Ascomycota fungus to producing an ascocarp as soil conditions dry out Ascomycota is a division or phylum of Fungi commonly known as Sac Fungi Ascocarps contain millions of asci each of which typically contains four to eight ascospores Ascospores have the ability to lay dormant slowing their metabolism and allowing them to survive off of almost nothing 6 What is chitin in words rather than a chemical rendering It is the cell wall of Fungi 7 Compare septate with coenocytic and sketch each simply fig 22 3b Septate has cross walls that separate nuclei Coenocytic lacks these cross walls and has many nuclei sharing the same space 8 How is it possible that a line or ring of mushrooms seemed to spring up overnight think about growth rates The ring is formed because of the shape of the mycorrhizae grows circular and out During stressful times for the fungi the fungi resorts to sexual reproduction in which the growth rates are increased 9 In the fungi under what conditions does asexual reproduction occur and under what conditions does sexual reproduction occur Asexual reproduction occurs when the Fungi are in a favorable environment Non stressful Sexual reproduction occurs when Fungi find themselves in a stressful environment Low Nitrogen Levels a can anything be generalized here to other kingdoms Yes this trend of reproduction is the same across the kingdoms a how are fragmentation and mitospores involved in reproduction Fragmentation Fragmentation of Hyphae begins by thickening the wall between hyphal cells and closing the septal pore Once the cell wall is thickened they begin to fragment and become their own cells Used in A sexual reproduction If the hyphae is broken off and then able to grow itself it is due to fragmentation Mitospores are spores formed through mitosis used for A Sexual reproduction 10 What often triggers sexual reproduction in the fungi A stressful environment a Why do you think this condition may have evolved To increase gene flow and ensure the survival of their species and to increase fitness a what are some examples of stress to a fungus A low Nitrogen environment lack of water lack of food 11 What comes before and what comes after the heterokaryotic dikaryotic condition in most fungi choose from plasmogamy karyogamy meiosis Plasmogamy comes before Heterokayrotic then Karyogamy comes and then meiosis occurs Plasmogamy 1st Dikaryotic 2nd Karyogomy 3rd Meiosis 4th 12 What are the six groups of fungi technical and common names taken up in lecture and give one distinguishing feature of each see fig 22 11 Microsporidia Obligate intracellular parasites lack mitochondria have a polar tube that is used to infect the organism