• All living organisms can be grouped or ‘classified’ using a classification system that consists of?five kingdoms. These five kingdoms are:
  • Animals
  • Plants
  • Fungi
  • Protoctists
  • Prokaryotes

   

• The?prokaryotes?are?different?from the other four kingdoms (which are all eukaryotes) as prokaryotic organisms are?always single-celled?and?do not contain a nucleus
• Instead, the?nuclear material?of prokaryotic cells is found in the?cytoplasm
• Bacteria?are prokaryotic organisms

Bacteria

• Bacteria, which have a wide variety of shapes and sizes, all share the following biological characteristics:
  • They are?microscopic single-celled organisms
  • They have a?cell wall?(not?made of?cellulose),?cell membrane,?cytoplasm?and?plasmids
  • They?lack a nucleus?but contain a?circular chromosome of DNA
  • They?lack mitochondria and other membrane-bound organelles?found in eukaryotic cells

   

• Examples of bacteria include:
  • Lactobacillus?(a rod-shaped bacterium used in the production of yoghurt from milk)
  • Pneumococcus?(a spherical bacterium that acts as the pathogen causing pneumonia)

   

• Bacteria?feed?in?different ways:
  • Some bacteria can carry out?photosynthesis
  • Most feed on other?living or dead organisms?(if they feed on?dead organic matter?then they are known as?saprobionts?or?decomposers)

   

A typical bacterial cell

Prokaryotic Cells Table