2.1 c - identification and taxonomy

• identification of an organism in a sample can be made by

  • classification guides
  • biological keys
  • analysis of DNA or protein
• organisms can be identified by

  • taxonomy
  • phylogenetics
• a biological key is used to identify the characteristics of different groups within a classification system, which are then compared with those of unknown specimens.
• DNA analysis involves comparing the genetic material from known samples with that of unknown ones using techniques such as PCR (polymerase chain reaction) and sequencing.
• taxonomy involves the identification and naming of organisms and their classification into groups based on shared characteristics
• classic taxonomy classification is based on morphology
• morphology is the form, shape and structure of organisms
• phylogenetics is the study of evolutionary history and relationships among individuals or groups of organisms
• phylogenetics is the changing of traditional classification of many organisms
• phylogenetics uses heritable traits to create a phylogeny (phylogenetic tree) which is a diagrammatic hypothesis of its relationship to other organisms

  • morphology
  • DNA sequences
  • protein structure
• genetic evidence can reveal relatedness obscured by divergent or convergent evolution
• model organisms those that are either easily studied or have been well studied
• model organisms are important in the advancement of modern biology
• bacterium

  e coli
• flowering plant

  arabidopsis thaliana
• nematode

  c elagans
• arthropod

  drosophila melanogaster
• chordates

  mice, rats and zebrafish