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Ch1 - The Evolution of Microorganisms and Microbiology What...

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The Evolution of Microorganisms and Microbiology
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What Are Microorganisms? Bacteria & Archaea Protists Fungi yeasts and molds Algae Multi-cellular organisms: flukes, tapeworms, etc. Viruses Viroids & Prions http://www.sdnhm.org/exhibits/epidemi c/teachers/museum-microbe.html
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What Are Microorganisms? 1. Giardiasis protist 2. Influenza virus 3. Food poisoning bacterium 4. Malaria protist 5. Strep throat bacterium 6. HIV/AIDS virus 7. Tuberculosis bacterium 8. Lyme disease bacterium 9. Hepatitis B virus http://www.sdnhm.org/exhibits/epidemi c/teachers/museum-microbe.html
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Kingdom Taxonomic System* 2 Kingdoms (Linnaeus) Plants & animals 3 Kingdoms (1866-1957) (Haeckel) Plants, animals, & protists Bacteria were thought to be unicellular plants 5 Kingdoms (until 1970’s) (Whittaker) Plants, animals, protists, fungi, bacteria * Viruses, viroids & prions are acellular and thus, are not represented in this model
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Domain Taxonomic System* Two Superdomains: Prokaryotes: Domain Bacteria Domain Archaea Eukaryotes: Domain Eukarya Includes fungi, protists, algae * Viruses, viroids & prions are acellular and thus, are not represented in this “universal tree of life”
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Taxonomy Schemes The ‘old’ 5 Kingdoms: Based primarily on phenetic observations Membrane presence Cell size Cell organization Animalia (E), Plantae (E), Fungi (E), Protista (E), & Monera (P) The ‘new’ 3 Domains: Based primarily on phylogenetic sequences rRNA DNA Protein Bacteria (P), Archaea (P), & Eukarya (E) E = Eukaryote; P = Prokaryote
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Why The Change In Schemes? Advances in electron microscopy has provided detailed cellular structures & cell organization Wealth of knowledge on microbial biochemistry & physiology Advances in molecular biology & computers have allowed sequencing of nucleic acids and proteins and their comparison rRNA is universally present in all living organisms Eukaryotes have slightly larger (18S) SSU rRNA than prokaryotes (16S) rRNA function is identical in all organisms
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Domains: rRNA Comparisons Bacteria (16S) Archaea (16S) Eukarya (18S)
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Superdomain Comparison Prokaryotes: Exist as only unicellular organisms Lack membrane- bound organelles Condensed region of DNA is not bound by a membrane nucleoid Eukaryotes: Can be unicellular or multi-cellular Have membrane- bound organelles Condensed region of DNA is also bound by a membrane nucleus
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Domain Bacteria Several morphologies coccus, bacillus, vibrio, spirochete, & spirillum Few are pleomorphic Size: 0.3 – 2.0 μm Rigid cell walls; contain peptidoglycan Reproduce by binary fission Motile by means of a flagellum/flagella
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Domain Archaea Morphologies and size are similar to bacteria Rigid cell walls; lack peptidoglycan and have unique membrane lipids Reproduce by binary fission Motile by means of a flagellum/flagella Often live in extreme environments
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Domain Eukarya: Single cells and multicellular organisms Saprophytic: live off
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