Aspetic technique

• What are the 2 main ways bacteria can be cultured

  • In a nutrient broth solution inside culture vial
  • On agar plate
• What does the broth solution + agar plate contain

  • Carbohydrates for energy
  • Nitrogen for protein synthesis
  • Other minerals + vitamins
• Why should we avoid contamination

  It would compete for nutrients in the culture vessels + also could be harmful
• What are aseptic techniques

  A special set of processes to avoid contamination
• What is an autoclave used for

  • Machine that uses steam at high temp + pressure killing all microorganisms
  • Sterilises petri-dish + growth mediums
• How can you prevent microbes from the air entering Petri dish or culture vial

  • Only briefly removing the lid at times
  • Tightly taping lid on
  • Turning on a bunsen burner to create a convection current
  • Put neck of culture vial through bunsen burner
• How is an inoculating loop sterilised

  • Passing it through a hot flame
• Why are Petri dishes stored upside down

  To stop condensation falling on agar
• Describe 2 ways bacteria can be transferred to an agar plate

  • Bacteria can be streaked onto plates using loop + allowed to form individuals colonies
  • Bacteria can be spread all over agar plate to form lawn of bacterial growth
• Describe the method for studying bacterial growth

  • Use a pen to plot the lid of Petri dish into 3 sections + label one of them control and the other 2, the other antibiotic/antisceptic
  • Sterilise forceps by passing it through flame
  • Use forceps to pick up a small filter paper disc + place into beaker of water
  • Repeat for the other 2
  • Tape lid onto plate + leave for 2 days at 25°C
  • When you come back, inhibition zone would be made clear
  • The more effective it is, the larger the zone
• What area of the body does antibiotics kill

  Kills bacteria INSIDE body
• What area of the body do antiseptics kill

  bacteria OUTSIDE of body
• What is the inhibition zone

  The clear zone where bacteria has been killed
• How do you know if the antiseptic or antibiotic is effective

  The more effective it is -> the larger the inhibition zone
• How do you work out the inhibition zone

  using the pi x r^2