Classification

Classification

1. Basics

   • Grouping together organisms
     • Classification is the act of arranging organisms into groups based on their similarities and differences.
       • Makes it easier for scientists to identify then and to study them
       • Taxonomy is the study of classification
     • Taxonomic hierarchy
       • Domain, Kingdoms, Phylum, Class, Order, Family, Genus, Species
   • Five kingdoms
     • Prokaryotae
       • Prokaryotic, unicellular, no nucleus, less than 5um
     • Protoctista
       • Eukaryotic cells, live in water, single or simple multicellular
     • Fungi
       • Eukaryotic, chitin cell walls, saprotropic, multinucleate
     • Animalia
       • Eukaryotic, multicellular, heterotropic, no cell walls
     • Plantae
       • Eukaryotic, multicellular, cell walls made of cellulose, photosynthesise, contain chlorophyll and are autotropic
   • Phylogeny
     • Is the study of the evolutionary history of groups of organisms.
       • It tells us who's related to whom and how closely related they are

2. Evolution of classification

   • Range of evidence
     • Molecular evidence - similarities in proteins and DNA.
     • Embryological evidence - similarities in early stages of development
     • Anatomical evidence - structure and function of the body
     • Behavioural evidence - behaviour and social organisation
     • New technologies can result in new discoveries
   • Three domains
     • Organism with a nucleus are in the domain Eukarya. Organisms without a nucleus (Prokayotic) are in both Archaea and Bacteria
     • The 3 domains were proposed because of new evidence. The Prokayotae were into two domains as evidence showed large differences between Archaea and Bacteria
       • Molecular evidence - Based on differences in RNA
       • Cell membrane evidence - Differences in bonds of lipids