Micro-organisms (2.7)

• What is binary fission?

  Asexual reproduction of bacteria
• How often can bacteria replicate through binary fission?

  Every 20 minutes
• How is replication affected?

  Temperature and availability of nutrients
• What does culture mean?

  To deliberately grow something by humans
• What ways can we culture bacteria?

  Nutrient broth solution or colonies on an agar plate
• What does nutrient broth solution do?

  Allows liquid or gel to provide nutrients for the bacteria to grow
• What must the nutrient broth include?

  Carbohydrates (energy) and nitrogen
• What are agar plates?

  A petri dish that contains agar gel and some nutrients
• What are agar plates used for?

  Culturing bacteria in the lab
• How are agar plates made?

  Pouring hot molten agar into a sterile petri dish, then allowed to set
• Why is it important for aseptic techniques to be used when culturing bacteria?

  Prevents contamination of other bacterium
• How is an inoculating loop sterilised?

  Heating a Bunsen burner to the red flame before and after use
• How do you prevent contamination when opening the lid of the petri dish?

  Don't fully remove the lid but tilt it to the side. It prevents micro organisms from contaminating the culture
• After inoculation what should happen to the petri dish?

  Secured in place with tape and labelled and dated
• What temperature and how long are inoculated agar plates incubated at?

  25 degrees Celsius for no longer than 24-48 hours so that pathogens cannot grow
• What temperature do pathogens thrive at?

  37 degrees Celsius
• Why should all instruments be sterilised after use?

  Prevents contamination
• How can the rate of bacterial growth be reduced?

  Reducing temperature e.g keeping food in a fridge
• What are fermenters?

  Containers used to grow bacteria and fungi in large amounts
• How is penicillin created?

  Penicillium mould
• What are fermenters made out of?

  Metals e.g stainless steel
• What does a steam inlet do and why?

  Produces hot steam which sterilises the interior of the fermenter to prevent contamination
• What does a nutrient inlet do and why?

  Allows sterile nutrients to enter the fermenter because penicillium needs nutrients to grow
• What does a water jacket do and why?

  Keeps the temperature inside constant because penicillium grows best at 23-28 degrees Celsius
• What does an air inlet do and why?

  Provides a source of oxygen so that the penicillium can respire aerobically
• What does the filter on an air inlet do and why?

  Stops micro organisms from entering the fermenter to prevent contamination
• What do stirring paddles do and why?

  Keeps mixture stirred to keep temperature constant
• What does a pH probe do and why?

  Monitors pH to check it is at optimum value because penicillium needs to be maintained at a pH of 6.5
• How long is penicillium left in the fermenter?

  200 hours