Linnaean System

• Linnaean System

  • 1 main systems we use, hierarchical + constantly updated to make as natural as possible
  • Invented by Swedish scientist from 18th century - Carl Linnaeus
  • Biggest group is Kingdoms, of which there are 5:
  • Animal
  • Plant
  • Fungi
  • Prokaryotes (bacteria + similar microbes)
  • Protoctisits (simple single-celled organisms)
  • In each kingdom, organisms are sorted out into smaller + smaller groups based on their similarities and differences
  • King Prawn Curry Or Fat Greasy Sausages
  • Classification of man:
  • Kingdom: Animals
  • Phylum: Vertebrates
  • Class: Mammals
  • Order: Primates
  • Family: Apes
  • Genus: Homo (meaning “man”)
  • Species: sapiens (meaning “wise”)
  • Species
  • Organisms' group w/ many common physical characteristics
  • That may interbreed + produce fertile offspring
  • Binomial system; referred in latin by genus + species
  • Classification constantly changes due to knowledge inc
• Classifying Plants

  • Historical reasons; plant biologists have divisions instead of phyla - apart from that system is same as animals
  • Moss division (Bryophytes)
  • No proper roots, simple stem + leaves

  Vascular plant division

  • True roots + stem w/ transport system + veiny leaves
  • Division 1
  • Pterophytes: fern class, wing-like leaves, reproduce w/ spores, young leaves roll into “fiddleheads” not buds
  • Division 2
  • Gymnosperms: Conifer class, needle-shaped leaves + seeds form in cones
  • Angiosperms: Flowering plant class, broad leaves, seeds form in flowers + split to 2 orders
  • Monocotyledons: parallel veined leaves (like grass), seed w/ 1 grain + 1 embryonic leaf
  • Dicotyledons: branching veined leaves, seed w/ 2 grains + 2 embryonic leaves
• 3 Domain System

  • Evolutionary classification model
  • Uses Linnaean system, but adds extra taxon above Kingdom – domain
  • Based rRNA nucleotide sequence differences + cell's membrane lipid structure
  • Comparing rRNA structure is useful as rRNA molecules through nature carry out same function + changes little over time
  • Similarities/dissimilarities are good indication of how related different cells/organisms are
  • Proposes common ancestor cell gave rise to 3 different cell types, each representing a domain
  • 3 domains
  • Archaea (archaebacteria)
  • Bacteria (eubacteria)
  • Eukarya (eukaryotes)
  • Eukarya then divide into 4 kingdoms: Protoctists, Fungi, Animalia, and Plantae
  • Another way to look at classification is by observing phylogeny or organisms evolutionary history
• Phylogenetic or Evolutionary Species Concept

  • Species further defined:
  • Organism group who share common evolutionary history + have similar morphology, physiology + behaviour
  • Share same ecological niche
  • Can interbreed + produce fertile offspring
  • Uses molecular biology techniques to compare DNA, RNA + protein structure
  • E.g. cytochrome C; essential for aerobic respiration
  • Proteins AA sequence is identical in humans + chimpanzees
  • Rhesus monkey sequence different by 1 AA
  • Dogfish sequence is different by 11 AA
  • Compare proteins by immunological responses

  1. Rabbit injected with human blood
  2. After time, rabbit blood serum collected w/ antibodies to human proteins
  3. Rabbit serum added to human serum - 100% precipitation
  4. Added to chimp serum - 97%
  5. Added to gorilla serum - 96%
  6. Added to gibbon serum - 79%

  • 2 main advantages over Linnaean system
  • Tells you it's evolutionary history
  • Doesn't try rank organisms