Biodiversity And Classification Of Micro Organisms

• Micro Organisms Cannot be seen with the naked eye.

  Micro = small
• There are four types of micro organisms:

  • Viruses
  • Bacteria
  • Protists
  • Fungi
• Favourable conditions for micro organisms to grow and multiply:

  • Sufficient food
  • Moisture
  • Optimum temperature
• Pathogens: micro- organisms that cause disease
• All viruses are pathogens and some bacteria
• The only living characteristic a virus contains is reproduction
• The final phase of an HIV infection is AIDs
• AIDs is a virus that targets the immune system
• HIV stands for human immunodeficiency virus
• Some bacteria are beneficial as they produce antibiotics which kill other bacteria
• Bacteria can be found everywhere on earth, they live in soil, water, air, plants and animals.
• Microorganisms are the most abundant on earth and are found in large numbers in every environment
• The cell structure of microorganisms:

  • Viruses = neither prokaryotic or eukaryotic, are acellular
  • Bacteria = prokaryotic, are unicellular
  • Protists = eukaryotic, mostly unicellular organisms
  • Fungi =eukaryotic, are unicellular and multicellular
• Difference between Prokaryotes and Eukaryotes:

  Prokaryotes:

  • Organisms without a true nucleus
  • DNA is not enclosed by a nuclear membrane and occurs freely in the cytoplasm
  • Membrane-bound organelles are absent

  Eukaryotes :

  • Organisms with a true nucleus
  • DNA is enclosed by a nuclear membrane inside the nucleus
  • Membrane-bound organelles occur in the cytoplasm
• Viruses have properties of both living and nonliving organisms
• Viruses only reproduce inside cells of living organisms
• Viruses are dormant (inactive) outside a living cell
• Viruses only attack certain parts and organisms, thus they are host-specific and some are tissue-specific
• Viruses reproduce by converting the genetic material (DNA or RNA) of the host cells into viral nucleic acids so that new viruses can be produced
• Viruses contain DNA or RNA, never both
• A virus that infected a bacterial cell is called a bacteriophage
• The structure of a virus in words:

  Consists of nucleic acid that are in the centre, surrounded by a protein capsule. When entering a host it receives a protective layer called a shealth.
• Bacteria occur in almost any imaginable habitat on earth
• Aerobic bacteria: live in the presence of oxygen.

  Anaerobic bacteria: live in the absence of oxygen
• Monera

  • Prokaryotes
  • Organisms without a true nucleus
  • Their DNA is not enclosed by a nuclear membrane and occurs freely in the cytoplasm
  • Membrane-bound organelles are absent
• Biodiversity

  The variety of living organisms
• Living organisms

  • Monera
  • Protista
  • Fungi
  • Plantae
  • Animalia
• Eukaryotes


  • Organisms with a true nucleus
  • Their DNA is enclosed by a nuclear membrane inside the nucleus
  • Membrane-bound organelles occur in the cytoplasm
• Favourable conditions for the growth and multiplication of microorganisms

  • Sufficient food
  • Moisture
  • Optimum temperature
• Some microorganisms cause disease and are known as pathogens
• Groups of microorganisms

  • Viruses
  • Bacteria
  • Protists
  • Fungi
• All viruses and some bacteria, protists, and fungi are pathogenic in nature
• Viruses do not consist of cells and are not classified as prokaryotes or eukaryotes
• According to the theory of evolution, all life forms developed from unicellular microorganisms over millions of years
• A virus that infects a bacterial cell is called a bacteriophage
• Shapes of viruses

  • Rod-shaped
  • Spherical
  • Complex shapes
• A well-known plant virus is the tobacco mosaic virus (TMV). In humans, diseases like AIDS, colds, flu, rabies, measles, and polio are caused by viruses
• Viruses

  Difficult to classify, have properties of both non-living particles and living organisms
• Most pathogens are parasites and live in or on other organisms
• Viruses can only reproduce inside cells of living organisms