Viruses, Bacteria, FungiToday…VIRUSESVirus structureVirus is a cellular parasiteViruses cause diseasesHuman VirusesPlant VirusesKingdomsFive KingdomsLiving organismsPROKARYOTESBacteriaSlide 14Bacterial pathogensBacterial controlBeneficial BacteriaEukaryotesEndosymbiont TheoryEndosymbiont Theory (p.26, box 2.2)Kingdom FungiFungal morphologyFungi Hyphae: filamentsFungal structure and reproductionFungal fruiting bodiesSignificance of FungiMycorrhizaeFungi act as antibioticsPathogenic fungiPathogenic fungi: MycotoxinsSlide 31Plant Diseases caused by fungiFungal plant pathogensIrish potato famineCommercial uses of fungiSlide 36Slide 37Slide 38Edible fungiOther types of fungusViruses, Bacteria, FungiDiversity of LifeDiversity of LifeToday…•Viruses•Prokaryotes: Kingdom Monera•Eukaryotes•FungiVIRUSES•Viruses are non-living organisms.•Technically they are not considered living organisms, since they cannot self replicate (they’re not a kingdom)•Remember that living organisms:1. Are highly organized2. Stable chemical composition3. Take energy & use it4. Respond to stimuli5. Grow & develop6. Able to self reproduce (sexually or asexually)7. Show genetic variation8. Adapt to their environmentsVirus structure•Viruses: Just a protein coat for protection (capsid) and a nucleic acid (RNA or DNA) for information on how to make more copies of the same virus•Cannot replicate/reproduce onits own! Needs a host…Virus is a cellular parasite•Uses cell machinery of a host cell to replicate and to produce more viruses•They come in many varieties, sizes & shapesViruses cause diseases•Viruses cause numerous diseases in Plants, animals, bacteria & fungi…•Examples of human viruses:•Herpes virus•Hepatitis virus•Rabies•Ebola – emerging epidemics•Influenza (“flu”) – respiratory infection (fever, headache, chills, cough, stuffy nose, sore throat) caused by a variety of viruses. Flu season: Nov. – March. •Passed on by sneezing, coughing – air, hand-to-mouth, etc. •Vaccine helps prevent outbreaks.Human Viruses•Human Immunodeficiency Virus (HIV) – causes AIDS. •Transmitted through sexual contact, sharing infected needles, blood transfusions, mother to baby.•Severe Acute Respiratory Syndrome (SARS) – brand new deadly virus, started in China, causes atypical pneumonia. Spreads quickly.Plant Viruses•Tobacco Mosaic Virus (TMV) causes mottling symptoms•Rose mosaic virus•Spots on fruit•Wheat stunt virusKingdoms•We learned last week that living organisms are divided into kingdoms…Kingdom Division Class Order Family Genus Species•Taxonomic hierarchy for classifying organisms•Scientific name = Genus + SpeciesFive Kingdoms•Living organisms are classified in five kingdoms:•Monera: bacteria, originally classified as plants because they have cell walls•Protista: algae, slime molds, protozoa (have a cell wall, not cellulose)•Fungi: mold, mildew, mushrooms. In past were class. as plants because they have cell walls and are ‘rooted’ in ground •Plantae: Complex multicellulareukaryotes, obtain nutrients byphotosynthesis•Animalia: Complex multicellular eukaryotes, obtain food by ingestionLiving organisms•PROKARYOTIC – Lack membrane-bound organelles–Kingdom Monera•EUKARYOTIC – have membrane bound organelles.–Kingdoms Protista, Plantae, Fungi, AnimaliaPROKARYOTES•Bacteria are small and unicellular•They have no internal organelles (no chloroplasts, nucleus, ER, mitochondria)•Haploid (n) onlyBacteria•Replication is asexual – clonal, rapid simple division (no mitosis)•Pseudo-sexual reproduction, has means for Genetic exchange•Called conjugationBacteria•Bacterial forms: cocci, bacilli, spirilli•Some forms are photosynthetic: cyanobacteriaBacterial pathogens•Animal pathogens:•Typhoid, tuberculosis•Bubonic plague or “Black Death”,transmitted by fleas (caused 25 million deaths in Medieval Europe)•Syphilis, gonorrea (venereal diseases)•E. coli, Salmonella (food poisoning)76 million illnesses worldwideBacterial control•There are ways of controlling bacterial growth: •Disinfectants •Antibiotics •Low temperatures•High temperatures, •Low oxygenBeneficial Bacteria •Nitrogen-fixation – convert atmospheric N into useful Nitrogen (N gas  plants  animals)•Decomposition in the biosphere – get rid of dead organisms, nature’s recyclers•Intestinal Bacteria – supply vitamins (K)•Commercial use: yogurt, sour cream, fermentation•Genetically-engineered bacteria produce insulin and other important chemicals.•Can also help clean up oil spills: oil ‘eating’ bacteria!Eukaryotes•Four Kingdoms: Fungi, Protista, Plantae, Animalia•Have organelles (nucleus, mitochondria, etc.)•Arose from endosymbiosis•Endosymbiont TheoryEndosymbiont TheoryLooking at the differences between prokaryotes and eukaryotes…How did eukaryotic organisms evolve?How did chloroplasts and mitochondria evolve?Chloroplasts and mitochondria: •Same size as bacteria•Have their own DNA•Divide similarlyEndosymbiont Theory (p.26, box 2.2)•Chloroplasts and Mitochondria are descendants of once free-living prokaryotes that were engulfed by larger cells…establishing a symbiotic (mutually beneficial) relationship.Kingdom Fungi•Characteristics of fungi:•Eukaryotic•Non-photosynthetic, must obtain nutrients by absorption (produce digestive enzymes)•Have a cell wall! Fungi cell wall is made of chitin and/or cellulose•Occur in haploid (n) and diploid (2n) stages•Reproduce sexually and asexuallyFungal morphology•Most fungi come in thread-like strands, called hyphae (collectively called mycelium)•Other fungi are single-celled, called yeasts.•Form spores that can spread by wind, air or soil (give us allergies!)•Fungi are so successful because they can reproduce both sexually and asexually–Sexual spores – (by meiosis) mushroom is spore-producing structure, formed by many hyphae–Asexual spores (by mitosis)Fungi Hyphae: filamentsFungal structure and reproduction•Club fungi (mushrooms): Genetically compatible fungi fuse, combining cytoplasm and nuclei•Nuclei in the same cell do not fuse, producing a heterokaryotic (n+n) hyphae – which in turn forms the fruiting body (mushroom)•Underneath the cap, in the gills, n+n cells are called basidia•Nuclei combine, form a zygote which undergoes meiosis and produces haploid spores of diverse genotypes for