Viruses Bacteria Fungi Diversity of Life Today Viruses Prokaryotes Kingdom Monera Eukaryotes Fungi VIRUSES 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 2 3 4 5 6 7 8 Are highly organized Stable chemical composition Take energy use it Respond to stimuli Grow develop Able to self reproduce sexually or asexually Show genetic variation Adapt to their environments Virus 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 on its 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 shapes Viruses 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 virus Kingdoms 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 Species Five 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 multicellular eukaryotes obtain nutrients by photosynthesis Animalia Complex multicellular eukaryotes obtain food by ingestion Living organisms PROKARYOTIC Lack membrane bound organelles Kingdom Monera EUKARYOTIC have membrane bound organelles Kingdoms Protista Plantae Fungi Animalia PROKARYOTES Bacteria are small and unicellular They have no internal organelles no chloroplasts nucleus ER mitochondria Haploid n only Bacteria Replication is asexual clonal rapid simple division no mitosis Pseudo sexual reproduction has means for Genetic exchange Called conjugation Bacteria Bacterial forms cocci bacilli spirilli Some forms are photosynthetic cyanobacteria Bacterial 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 worldwide Bacterial control There are ways of controlling bacterial growth Disinfectants Antibiotics Low temperatures High temperatures Low oxygen Beneficial 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 Theory Endosymbiont Theory Looking 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 similarly Endosymbiont 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 asexually Fungal 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 sporeproducing structure formed by many hyphae Asexual spores by mitosis Fungi Hyphae filaments Fungal 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 dispersal See animation Fungal fruiting bodies Coalescence of many hyphae Role of spore production Mushrooms Have cap and stalk Spores are produced in the gills under the cap Significance of Fungi Many fungi are beneficial As decomposers fungi obtain nutrition from organic matter so they recycle nutrients Mycorrhizae Mycorrhizae fungus roots certain fungi grow into roots of most plants to supply water P and N 90 of plants need mycorrhyzae to survive An example of coevolution symbiotic relationship Fungus gets sugars from plants and fungus provides P and water to plant Fungi act as antibiotics Penicillin is produced by species of the fungus Penicillium which kills bacteria Discovered by Alexander Fleming in 1928 Left some unwashed plates with bacteria went on vacation and saw that a mold was growing inhibiting the growth of the bacterial colony Nobel Prize 1945 Pathogenic fungi Pathogenic fungi grow within a host using the host as food for replication Human Diseases Athlete s foot Yeast infections Ring worm Candidiasis Pathogenic fungi Mycotoxins Mycotoxins are harmful toxic chemicals produced by fungi and which accumulate in infected food Aflatoxins contaminate