classification

• Binomial system

  Universal method to name organisms, where the first part is the genus and the second part is the species
• Binomial names are written in italics, with the genus capitalised and the species not capitalised
• Advantage of binomial system

  • Gives a better indication of how closely related organisms are
  • Common names can be misleading
• Similar physical features between species

  Due to similar environmental selection pressures and shared ancestral alleles
• Hierarchy in classification

  • Small groups arranged within larger groups
  • No overlap between groups
• Taxonomic levels

  • Domain
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
• Purpose of classification

  • Organise the millions of species
  • Understand relationships and track changes (evolution, climate, human impacts)
• Methods of classification

  • DNA base sequence similarity
  • mRNA base sequence similarity
  • Amino acid sequence similarity
  • Immunological comparisons
• Phylogenetic classification

  • Groups organisms based on evolutionary origins and relationships
  • Identifies common ancestors shared by different species
• Phylogenetic trees show the most recent common ancestor between species
• Binomial System - Genus

  The first part of the binomial name, which is capitalized, refers to the genus or group of closely related organisms.
• Binomial System - Species

  The second part of the binomial name, which is not capitalized, refers to the specific species within that genus.
• Binomial System - Advantage 1

  Standardization: The binomial system provides a standardized way of naming organisms, which makes it easier for scientists around the world to communicate about them.
• Binomial System - Advantage 3

  Uniqueness: Each binomial name is unique to a particular species, which helps to avoid confusion and ensures that there is no ambiguity about which organism is being referred to.
• Binomial System - Advantage 2

  Precision: The binomial system gives a more precise and accurate indication of how closely related organisms are than common names, which can be misleading.
• DNA base sequence similarity

  A method of classification that compares the order of nucleotide bases (A, T, C, G) in the DNA sequence of different organisms. The more similar the DNA sequences are, the more closely related the organisms are likely to be.
• mRNA base sequence similarity


  A method of classification that compares the order of nucleotide bases in the mRNA (messenger RNA) of different organisms. Since mRNA is the template for protein synthesis, this method can also provide information about the similarity of proteins between organisms.
• Amino acid sequence similarity

  A method of classification that compares the sequence of amino acids in proteins between different organisms. Since the genetic code specifies the sequence of amino acids in a protein, this method can also provide information about the similarity of DNA or mRNA sequences between organisms.
• Immunological comparisons


  A method of classification that involves comparing the immune response of different organisms to a particular antigen. If two organisms have a similar immune response, it suggests that they have similar antigens or antigen-binding sites, which can indicate a close evolutionary relationship.