4.3

• Taxonomy: the study of classification
• Taxonomic hierarchy

  Eight levels called taxonomic groups: Similar organisms

  • Domains
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
• Kingdoms

  • Prokaryotae
  • Protocista
  • Fungi
  • Plantae
  • Animalia
• Prokaryotae

  Bacteria

  • prokaryotic
  • unicellular
  • no nucleus
• Protoctista

  Algae

  • eukaryotic
  • singled cells
  • usually live in water
• Fungi

  Yeast

  • eukaryotic
  • chitin cell wall
  • saprotrophic (absorb substances from dead organisms)
  • Single-celled / multicellular
• Plantae

  Ferns

  • eukaryotic
  • multicellular
  • cellulose cell walls
  • photosynthesise
  • contain chloroplast
• Animalia

  Insects

  • eukaryotic
  • multicellular
  • no cell walls
  • heterotrophic (consume plants and animals )
• Binomial Naming Systems : Genus + Species

  • italics / underlined
• Phylogeny: the study of the evolutionary history of a group of organisms.
• All organisms have evolved from shared common ancestor
• According to phylogenetics

  a species is the smallest group that shares a common ancestor
• Classification system takes into account phylogeny

  Classification organisms in this way is known as cladistics
• Early classification 


  • only used observable features
  • problems: don't always agree on relative importance and physical features don't show how they are related
• Molecular evidence

  similarities in proteins and DNA

  • compare how DNA is stored and the sequence of DNA bases
  • compare sequences of amino acids in proteins from different organisms
• Embryological evidence

  similarities in early stages of an organism's development
• Anatomical evidence

  similarities in the structure and function of different body parts
• Behavioural evidence

  similarities in behaviour and social organisation of organisms
• What are the 3 Domains?

  Archaea

  Eukarya

  Bacteria
• prokaryote are separated into bacteria and archaea
• Eukarya contain a nucleus
• Molecular evidence

  The enzyme RNA polymerase is difference in bacteria and archaea

  Archaea, but not bacteria, have similar histones to Eukarya
• Cell membrane evidence

  the bonds in lipids in the cell membrane of bacteria and archaea are different

  the development and composition of flagellum are also different