Bacteria

• Bacteria


  • Some of the smallest living organisms
  • Cannot be seen without a microscope
  • Each bacterium is a single cell
• Bacterial cell


  • Looks different to plant and animal cells
  • Don't have a proper nucleus
  • Have a loop in the cytoplasm that carries out genetic information
  • Have small pieces of genetic information called plasmid
• Bacteria are living organisms
• Bacteria


  • Some are useful
  • Some can cause disease to humans, plants and animals
• Bacteria that cause disease


  • Salmonella bacteria causes stomach ache
  • Bean Blight is caused by bacteria
• Useful bacteria


  • Bacteria can help to decay the dead bodies of plants and animals
  • Bacteria in our guts and our skin help to keep us healthy
• Growing bacteria


  1. Grow on a special jelly that contains all the food they need

  2. They will form colonies that are big enough to be seen without a light microscope
• Sterilizing the inoculating loop


  1. Heat the loop until it's red hot in the flame of the Bunsen burner

  2. Let it cool

  3. Do not blow on it or put the loop down
• Inoculating the agar


  1. Dip the inoculating loop in a suspension of the bacteria you want to grow

  2. Use the loop to make zigzag streaks on the surface of the agar
• Sealing the petri dish


  1. Seal the petri dish with the lid

  2. Wrap it with adhesive tape to prevent micro-organisms from the air contaminating the culture

  3. Do not seal all the way so oxygen can still come through the dish