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3.2 distinguish between:

distinguish between:

  • prions
  • viruses
  • bacteria
  • protozoans
  • fungi
  • macro-parasites

and name one example of a disease caused by each type of pathogen

Pathogen Description Examples of diseases it causes
Prions Protein that has been altered from its normal structure and can then alter other proteins to develop more prions, so that the change spreads like a chain reaction.
  • scrapie in sheep
  • spongiform encephelopathy in cattle (mad cow disease)
  • Creutzfeldt-Jakob (CJD) disease in humans
Viruses Consist of DNA or RNA enclosed in protein, live inside living cells. They are so small that they cannot be seen with a light microscope.
  • influenza
  • measles
  • a common cold
  • herpes
  • AIDS
  • Warts
  • Hepatitis
  • Foot-and-mouth disease
  • Plum pox virus
Bacteria Very simple cells with no internal membranes.
  • Boils
  • Cholera
  • Legionnaire’s disease
  • Tuberculosis
  • Crown gall blight
Protozoans Microscopic single-celled organisms with internal membranes.
  • Amoebic dysentery
  • Giardia,
  • Malaria,
Fungi Heterotrophic organisms. Some (e.g. yeasts) are unicellular, others consist of long branching threads.
  • Ringworm
  • Tinea
  • Thrush
  • Many plant diseases such as damping off in seedlings
Macro-organisms Organisms that are visible to the naked eye, also called parasites.
  • fleas
  • ticks
  • tapeworms
  • bilharzia worms
  • hydatid worms
  • liver fluke
  • many plant parasites, e.g. aphids