LECTURE 3

• Taxonomy


  Science of biological classification
• Taxon/Taxa


  Group or level; hierarchy of different levels
• Systematics/Phylogeny


  Study of diversity and evolutionary relationships
• Dichotomous key


  Tool for assigning an organism to specific taxonomic category
• Taxonomic category/hierarchy


  Ordered group of taxonomics used to specify organisms from general to specific
• Unique taxonomic ID for each organism makes them easy to differentiate from others
• Major taxonomic characteristics


  • Morphological characters
  • Physiological characters
  • Geographic and behavioral characters
  • Molecular characters
  • Ecological characters
• Morphological characters


  General external morphology and internal (microscopic parts of organisms)
• Physiological characters


  Characters that determine the bodily functions of a microorganism, e.g. metabolic activities, body secretions
• Geographic and behavioral characters


  Where organisms live naturally, what they eat, and how they change with seasons
• Molecular characters


  Immunological distances, electrophoretic differences, DNA hybridization, DNA-RNA sequence
• Ecological characters


  Where organisms live naturally, what they eat, and how they change with seasons
• Components of taxonomy


  • Classification
  • Nomenclature
  • Identification
• Systems of classification


  • Artificial system
  • Natural system
  • Phylogenetic (Phyletic) system
• Artificial system


  Organisms have same characteristics but are not closely related
• Natural system


  Based on the relationship of organisms in terms of their morphological and anatomical similarity
• Phylogenetic (Phyletic) system


  Based exclusively on the relationship of organisms and how closely they are related based on ancestry
• Methods of classification


  • Phenotypic
  • Genotypic (Phylogenetic)
• Phenotypic classification


  Relatedness is based on observable same traits, not solely on genetics or evolution
• Genotypic (Phylogenetic) classification

  Relatedness is considered solely through the genome level or genetic-based
• Taxonomic categories


  • Family
  • Genus
  • Species
• Family


  Organisms have related characteristics or common attributes despite having many genera
• Species


  Population that can potentially interbreed freely within and among themselves, sharing the same physiological and genetic features that are uniquely different from other species
• Subspecies


  • Biotype
  • Serotype
  • Genotype
• Biotype


  Same or nearly same genotype, similar genetically
• Serotype


  Have the same type and number of antigens
• Genotype


  Have minor sameness of traits, sharing specific but relatively minor characteristics
• Clone


  Literally a clone product, individuals organisms derived from a single parent cell and are identical
• Strain


  • Serovar
  • Biovar
  • Morphovar
  • Isolate
• Serovar


  Strains differ in the type and number of antibodies they possess
• Biovar


  Strains differ in biochemical and other non-serological properties
• Morphovar


  Strains differ in morphological distinctions or features
• Isolate


  Pure culture derived from a heterogeneous and wild population of microorganisms
• Carolus Linnaeus introduced the formal system of classification dividing living organisms into two kingdoms: Plantae and Animalia
• International Code of Nomenclature of Bacteria (ICNB) or Bacteriological Code (BC) is used for naming prokaryotes
• Bergey's Manual of Systematic Bacteriology is used for naming prokaryotes
• Binomial nomenclature


  Microbial nomenclature rules are limited to genus and species
• Family and order suffixes are written as -ales and -aceae
• Genus is always capitalized and a noun, species is always lowercase and an adjective
• Genus can be abbreviated using the first letter capitalized followed by a period, but species cannot be abbreviated