classification chuchu

• There are 13 billion known species of organisms, which is only 5% of all organisms that ever lived
• New organisms are still being found and identified
• Classification


  The arrangement of organisms into orderly groups based on their similarities
• Taxonomy


  The science of classification
• Taxonomists


  Scientists that identify & name organisms
• Benefits of classifying


  • Accurately & uniformly names organisms
  • Prevents misnomers
  • Uses same language (Latin or some Greek) for all names
• Confusion can arise when using different languages for names
• Latin names are understood by all taxonomists
• Early taxonomists


  • Aristotle was the first taxonomist, dividing organisms into plants & animals based on their habitat
  • John Ray was the first to use Latin for naming, with very long descriptive names
• Carolus Linnaeus


  • 18th century taxonomist
  • Classified organisms by their structure
  • Developed the modern system of naming known as binomial nomenclature
• Binomial nomenclature


  Two-word name (Genus & species) in Latin or Greek, italicized in print, with genus capitalized and species not
• The International Code for Binomial Nomenclature contains the rules for naming organisms, and all names must be approved by International Naming Congresses
• Taxon (taxa-plural)


  A category into which related organisms are placed
• Hierarchy of taxonomic groups

  • Domain
  • Kingdom
  • Phylum (Division for plants)
  • Class
  • Order
  • Family
  • Genus
  • Species
• Archaea and Eubacteria are unicellular prokaryotes, while Eukarya are more complex with a nucleus and membrane-bound organelles
• Archaea


  • Probably the 1st cells to evolve, live in harsh environments
• Eubacteria


  • Some may cause disease, found in all habitats except harsh ones, important decomposers and commercially important
• Kingdoms in Domain Eukarya

  • Protista
  • Fungi
  • Plantae
  • Animalia
• Protista


  • Most are unicellular, some are multicellular and autotrophic or heterotrophic, aquatic
• Fungi


  • Multicellular (except yeast), absorptive heterotrophs, cell walls made of chitin
• Plantae


  • Multicellular, autotrophic, absorb sunlight for photosynthesis, cell walls made of cellulose
• Animalia


  • Multicellular, ingestive heterotrophs, feed on plants or animals
• Most genera contain a number of similar species, except the genus Homo which only contains modern humans
• Classification is based on evolutionary relationships
• Basis for modern taxonomy


  • Homologous structures
  • Similar embryo development
  • Molecular similarity in DNA, RNA, or amino acid sequence of proteins
• Homologous structures (same structure, different function) show similarities in mammals
• Similarities in vertebrate embryos also show evolutionary relationships
• Cladogram


  Diagram showing how organisms are related based on shared, derived characteristics such as feathers, hair, or scales
• Dichotomous keying


  Used to identify organisms by giving characteristics in pairs, reading both and either going to another set of characteristics or identifying the organism