Micro Ch 10

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Micro Ch 10

  1. 1. Chapter 10 Classification of Microorganisms
  2. 2. Taxonomy <ul><li>Taxonomy </li></ul><ul><ul><li>The science of classifying organisms </li></ul></ul><ul><ul><li>Provides universal names for organisms </li></ul></ul><ul><ul><li>Provides a reference for identifying organisms e.g from an infection </li></ul></ul><ul><li>Phylogeny </li></ul><ul><ul><li>The study of the evolutionary history of organisms </li></ul></ul>
  3. 3. History of Taxonomy <ul><li>1735 Plant and Animal Kingdoms </li></ul><ul><li>1857 Bacteria & fungi put in the Plant Kingdom </li></ul><ul><li>1866 Kingdom Protista proposed for bacteria, protozoa, algae, & fungi </li></ul><ul><li>1937 &quot;Prokaryote&quot; introduced for cells &quot;without a nucleus&quot; </li></ul><ul><li>1961 Prokaryote defined as cells in which nucleoplasm is not surrounded by a nuclear </li></ul><ul><li>membrane </li></ul><ul><li>1959 Kingdom Fungi </li></ul><ul><li>1968 Kingdom Prokaryotae proposed </li></ul><ul><li>1978 Two types of prokaryotic cells found (bacteria & Archae) </li></ul>
  4. 4. The Three-Domain System Figure 10.1
  5. 5. The Three-Domain System Table 10.1
  6. 6. Table 10.2
  7. 7. Endosymbiotic Theory: Origin of Eukaryotes Figure 10.3 Figure 10.2
  8. 8. Classification of Organisms <ul><li>Living organisms are grouped according to similar characteristics </li></ul><ul><li>Each organism is assigned a unique scientific name </li></ul><ul><li>Binomial nomenclature </li></ul><ul><ul><li>Every organism is assigned 2 names </li></ul></ul><ul><ul><li>genus name ; always capitalized, usually a noun </li></ul></ul><ul><ul><li>species name (specific epithet ); lowercase, usually an adjective </li></ul></ul><ul><ul><li>Both names are printed underlined or italicized </li></ul></ul><ul><ul><li>Example Homo sapiens; homo means man, sapiens means wise </li></ul></ul>
  9. 9. Examples of Scientific Names Honors Oswaldo Cruz Corkscrew-like (trypano-, borer; soma-body) Trypanosoma cruzi Spores spread in wind (nota) Tuftlike (penicill-) Penicillium notatum Forms pus (pyo-) Chains of cells (strepto-) Streptococcus pyogenes Stupor (typh-) in mice (muri-) Honors Daniel Salmon Salmonella typhimurium Disease in fish Honors Lois Pfiester Pfiesteria piscicida The disease Source of Specific epithet Honors Edwin Klebs Kbebsiella pneumoniae Source of Genus name Scientific binomial
  10. 10. Taxonomic Hierarchy Figure 10.5
  11. 11. Species Definition <ul><li>Eukaryotic species : </li></ul><ul><ul><li>A group of closely related organisms that breed among themselves </li></ul></ul><ul><li>Prokaryotic species : </li></ul><ul><ul><li>A population of cells with similar characteristics </li></ul></ul><ul><ul><li>Clone: Population of cells derived from a single cell </li></ul></ul><ul><ul><li>Strain: Genetically different cells within a clone </li></ul></ul><ul><li>Viral species : </li></ul><ul><ul><li>Population of viruses with similar characteristics that occupies a particular ecological niche </li></ul></ul>
  12. 12. <ul><li>Kingdom Animalia : </li></ul><ul><ul><li>Multicellular; no cell walls; chemoheterotrophic </li></ul></ul><ul><li>Kingdom Plantae: </li></ul><ul><ul><li>Multicellular; cellulose cell walls; usually photoautotrophic </li></ul></ul><ul><li>Kingdom Fungi: </li></ul><ul><ul><li>Unicellular or multicellular; Chemoheterotrophic; cell walls of chitin; develop from spores or hyphal fragments </li></ul></ul><ul><li>Kingdom Protista: </li></ul><ul><ul><li>A catchall for eukaryotic organisms that do not fit other kingdoms </li></ul></ul>Classification of Eukaryotes; Domain Eukarya
  13. 13. Classification of Viruses <ul><li>Are not classified as part of the 3 domains </li></ul><ul><li>Are not composed of cells </li></ul><ul><li>Use the host cells machinery to multiply </li></ul><ul><li>Are obligate intracellular parasites </li></ul>
  14. 14. Classification of Prokaryotes Figure 10.6
  15. 15. References <ul><li>Based on published articles </li></ul><ul><li>Approved Lists of Bacterial Names </li></ul><ul><li>Lists species of known prokaryotes </li></ul><ul><li>Based on rRNA sequencing </li></ul><ul><li>Bergey’s Manual of Systematic Bacteriology </li></ul><ul><li>Provides phylogenetic information on bacteria and archaea </li></ul><ul><li>Morphology, differential staining, biochemical tests </li></ul><ul><li>Bergey’s Manual of Determinative Bacteriology </li></ul><ul><li>Provides identification schemes for identifying bacteria and archaea </li></ul>
  16. 16. Identification Methods <ul><li>Morphological characteristics : Useful for identifying eukaryotes </li></ul><ul><li>Differential staining : Gram staining, acid-fast staining </li></ul><ul><li>Biochemical tests : Determines presence of bacterial enzymes </li></ul>Figure 10.8
  17. 17. Identification Methods <ul><li>Serology </li></ul><ul><ul><li>Combine known antiserum (antibodies) + unknown bacterium </li></ul></ul><ul><li>Phage typing </li></ul><ul><ul><li>Bacteriophages are bacterial viruses. They are specific for which bacteria they infect </li></ul></ul>Figure 10.10
  18. 18. <ul><li>DNA base composition </li></ul><ul><ul><li>Guanine + cytosine moles% (GC) </li></ul></ul><ul><li>DNA fingerprinting </li></ul><ul><ul><li>Electrophoresis of restriction enzyme digests </li></ul></ul><ul><li>rRNA sequencing </li></ul><ul><li>Polymerase Chain Reaction (PCR) </li></ul>Identification Methods Figure 10.14
  19. 19. Dichotomous Key

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