The 5 Kingdoms
The Five Kingdoms:
- Originally, organisms were grouped based on shared characteristics.
- Prokaryotae (e.g. Bacteria)
- Protoctista (e.g. Amoeba)
- Fungi (e.g. Yeast, mould, mushrooms)
- Plantae (e.g. plants)
- Animalia (e.g. animals)
Changes to Classification System:
- Originally classification was just based on observable characteristics.
- Now, with advances in science, unobservable similarities such as DNA and evolutionary relationships affect how organisms are classified.
- Currently, we use the three domain system - Eukarya, Archaea & Bacteria.
- Domains are a higher level of classification than Kingdoms and classify organisms based on the size of their ribosomes and types of RNA.
- Eukarya: 80s ribosomes, RNA polymerase contains 12 proteins.
- Archaea:70s ribosomes, RNA polymerase contains between 8 -10 proteins.
- Bacteria: 70s ribosomes, RNA polymerase contains 5 proteins.
- Archaebacteria can live in extreme environments such as extreme temperatures, anaerobic conditions and highly acidic conditions.
- Although Archaebacteria and Eubacteria are both single celled prokaryotes, they are in different kingdoms because they have different chemical makeup. For example eubacteria walls are made of peptidoglycan, whereas many archaebacteria have cell walls made of polysaccharide pseudomurein.
- Most known bacteria are eubacteria.