Classification and Taxonomy

• Species- a group of similar organisms that can breed together to create fertile offspring
• Three domains of life

  • Bacteria (true bacteria)
  • Archaea (non-bacteria prokaryotes)
  • Eukarya (Eukaryotes)
• Taxons:

  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
• Genus and species are used for binomial naming of a species
• 2 types of classification

  • Artificial
  • Phylogenetic classification
• Artificial classification

  • Organises organisms according to analogous characteristics
  • Have the same function, not the same evolutionary origins
  • E.g. butterflies and birds both fly
• Phylogenetic classification

  • Organises based on evolutionary origins and relationships
  • Groups are arranged in hierarchy
• advances in immunology and genome sequencing help to clarify evolutionary relationships between organisms
• Advances in technology can result in new discoveries and updates to the classification systems:

  • Genome sequencing
  • Comparing amino acid sequences
  • Immunological comparison
• Genome sequencing

  • Entire base sequences have been determined, allows for comparison between organisms
  • Closely related species have higher percentage of similarity
• Comparing amino acid sequences

  • The more similar the sequence, the closer related the organisms are
  • E.g. haemoglobin is found in many organisms
• Immunological comparison

  • Similar shaped proteins bind to the same antibodies
  • If proteins are similar among species, then the organisms could be closely related
  • antibodies and proteins form precipitate