2OutlineShared CharacteristicsThe Body of a FungusHow Fungi ReproduceHow Fungi Obtain NutrientsEcology of FungiFive Major Groups of FungiLichensMycorrhizaeEndophytesSymbioses
3Shared Characteristics Distinctive fungal featuresFungi are heterotrophs.Fungi have several cell types.Some fungi have a dikaryon stage.Fungi have cell walls that include chitin.Fungi undergo nuclear mitosis.
4The Body of a FungusFungi exist mainly in the form of slender filaments (hyphae).long chains of cells joined end-to-end divided by cross-walls (septa)rarely form complete barriercytoplasm freely streams in hyphaemycelium - mass of connected hyphaegrows through and penetrates substrate
5The Body of a FungusFungi cell walls are formed of polysaccharides and chitin.not cellulose like those of plantsMitosis is unique.nuclear envelope does not break down and re-formspindle apparatus formed withinspindle plaques take place of centrioles
6How Fungi ReproduceDiffer from most animals and plants in that each compartment of hypha can contain one, two or more nucleimonokaryotic - each compartment has a single nucleusdikaryotic - two distinct nuclei within each hyphae compartment
7How Fungi ReproducePossible for many nuclei to intermingle in common cytoplasm of fungal mycelium which can lack distinct cellsheterokaryotic – dikaryotic or multinucleate hypha has nuclei from genetically distinct individualshomokaryotic – hyphae whose nuclei are genetically similar to one another
8How Fungi ReproduceFungi are capable of both sexual and asexual reproduction.Fungi reproduce sexually after two hyphae of opposite mating type fuse.in some fungi fusion two haploid cells immediately results in diploid cell (2n)basidiomycetes and ascomycetes have dikaryotic stage (1n + 1n) before parental nuclei fuse to form diploid nucleus
9How Fungi ReproduceSpores most common means of reproductionmay form from asexual or sexual processesmost often dispersed by wind but some spread by insects or other small animalschytrids only group to retain ancestral flagella and motile zoospores
10How Fungi Obtain Nutrients All fungi obtain food by secreting digestive enzymes and then absorbing the organic molecules produced (external digestion).extensive hyphae network provides enormous surface area for absorptionmany fungi able to break down cellulose in wood
11Metabolic PathwaysAnaerobic fermentation provides flavor for wine and cheese.Biochemical manufacturing of organic substancesfoodpharmaceuticalsYeasts break down carbon-containing products.bioremediation
12Ecology of FungiFungi and bacteria are the principal decomposers in the biosphere.mineral cyclingFungi are virtually the only organisms capable of breaking down lignin.Fungi often act as disease-causing organisms for both plants and animals.agricultural damagehuman health
13Ecology of FungiMutualistic associationslichens - fungi and green algaemycorrhizae - fungi and plant roots
14Four Major Groups of Fungi ChytridiomycotaZygomycotaBasidiomycotaAscomycota
15Chytridiomycotaaquatic, flagellated fungimost closely related to ancestral fungi
16Zygomycotaincludes common bread moldsproduces temporarily dormant zygosporangiasexual reproduction occurs by fusion of gametangiaasexual reproduction most commonhyphae produce clumps of erect stalks - sporangiophoresform sporangia
18BasidiomycotaMost familiar fungi (mushrooms, toadstools, puffballs, rusts, and smuts)named for characteristic sexual reproductive structure, basidiumFour haploid products of meiosis incorporated into basidiosporesMycelium made up of monokaryotic hyphae is called primary mycelium.fusion of different mating types forms dikaryotic, secondary mycelium.
20AscomycotaVery large group including yeasts, common molds, and morelsNamed for reproductive structure ascushaploid zygotic nucleus formed withinasci differentiated with ascocarpAsexual reproduction takes place in conidia spores at the end of conidiophores.
22AscomycotaYeastsunicellular - most reproduction is asexual and takes place by cell fission or buddingferment carbohydratesplay a leading role in genetic research
23LichensLichens are symbiotic associations between a fungus and a photosynthetic partner.usually ascomycetesSpecialized fungal hyphae penetrate photosynthetic cells and transfer nutrients to fungal partner.Durable fungus, combined with photosynthetic properties, has enabled lichens to invade harsh climates.extremely sensitive to pollutants
24MycorrhizaeRoots of about 90% of all kinds of vascular plants are involved in mutualistic symbiotic relationships (mycorrhizae).arbuscular mycorrhizae - fungal hyphae penetrate outer cells of plant rootmost commonectomycorrhizae - hyphae surround, but do not penetrate, cell walls of roots
26EndophytesEndophytic fungi live inside plants in the intercellular spaces.some may protect their hosts from herbivores by producing chemical deterrents
27Mutualistic Animal Symbioses A range of mutualistic fungal-animal symbioses has been identified.ruminantsleaf-cutter ants
28Fungal Parasites and Pathogens Chytridiomycosis - emergent infectious disease in amphibianschytrid Batrachochytrium dendrobatidisAflatoxins - carcinogenic compounds produced by strains of Aspergillus flavusgrows on corn, peanuts, cotton seeds
29SummaryShared CharacteristicsThe Body of a FungusHow Fungi ReproduceHow Fungi Obtain NutrientsEcology of FungiFive Major Groups of FungiLichensMycorrhizaeEndophytesSymbioses