virus/pathogens

• Bacteria


  • Large microbe
  • Divide by splitting in two
  • May produce toxins to make us ill
• Causes of bacterial diseases: Salmonella, Gonorrhoea
• Viruses


  • Smallest microbe
  • Not alive
  • Live and reproduce inside cells
• Causes of viral diseases: Measles, HIV, Tobacco mosaic virus (TMV)
• Pathogens


  Microbes/microorganisms that cause diseases
• Communicable diseases


  Infectious diseases that can be passed from person to person
• Pathogens are spread by air, contact and water
• Louis Pasteur showed that microbes caused disease and developed vaccines
• Painkillers


  No effect on the pathogens but do reduce the symptoms of illness
• Destroying viruses is very difficult without damaging body tissue as they live inside cells
• Discovery of new drugs

  • Medicines used to be extracted from plants and microorganisms
  • Some bacteria are becoming resistant which is very concerning
  • Alexander Fleming discovered penicillin
• Placebo


  A tablet with no active medicine content
• Vaccines


  An inactive form of a pathogen used to prepare your immune system
• Antibiotics


  • Medicines that kill specific bacteria
  • Greatly reduced deaths from bacterial diseases
  • Cannot kill viruses
• Making new medicines


  1. Need to be checked for toxicity (safety), efficacy (effectiveness) and dose

  2. First trials are done using cells, tissues and live animals

  3. Clinical trials use healthy volunteers and patients: 1) Very low doses at start of trial, 2) If safe, more trials done, 3) In double blind trial some patients given placebo
• White blood cells


  • Phagocytosis - ingest microbes
  • Produce antibodies - chemicals to destroy microbes
  • Produce antitoxins - chemicals to cancel-out toxins made by pathogens
• The majority of the energy we use to function comes from molecules of glucose which were originally made by plants during photosynthesis
• To release this energy we use a process called cellular respiration