Viruses

• Viruses


  • Not cells, not living, but considered organisms
  • About 10,000 times smaller than animal cells
  • Can't reproduce by themselves, but can use a host cell's machinery to make copies of themselves
  • Burst the host cell to release new viruses
• Viruses colonizing and bursting host cells


  Damages the host's body and makes them feel ill
• Viral diseases covered


  • Measles
  • HIV
  • Tobacco mosaic virus
• Measles virus


  • Spread by droplets when an infected person coughs or sneezes
  • Causes a red rash and fever
  • Rare in the UK due to vaccination
• HIV


  • Human Immunodeficiency Virus
  • Spreads through sexual contact or sharing bodily fluids
  • Causes a deficient immune system
  • Initially causes flu-like symptoms, then weakens the immune system over time
  • Can develop into AIDS if left untreated
  • Treatable with antiretroviral drugs
• Tobacco mosaic virus (TMV)


  • Affects certain plant species like tobacco and tomato
  • Discolours patches on leaves, reducing photosynthesis and plant growth
• Viruses are quite hard to explain as they aren't cells and aren't living, but are still considered organisms