B5.3 Flashcards
What do Agar gel plates contain ?
Agal gel plates contain hot nutrient broth solution then are left to set to turn it into a jelly/gel (by using a chemical called agar) like consistency in a petri dish.
1 What is the first thing that must be done when culturing microorganisms?
First, you must sterilise all petri dishes , bacterial nutrient broth and agar.
This kills any unwanted microorganisms and prevents contamination.
2 How is bacteria transferred into the culture?
Bacteria is usually transferred by an inoculating loop into the culture, which must be sterilised first, by passing the inoculating loop through a bunsen burner flame.
Use the loop to evenly spread the bacteria onto the agar plate.
3 What do you do after the bacteria has been transferred onto the petri dish?
You attach the lid of the petri dish using adhesive tape.
This stops the lid from falling and unwanted microorganisms entering.
4 What do you do after adding the adhesive tape?
Finally, you place the agar plate upside down into an incubator.
This stops the moisture from dripping down onto the bacteria and disrupting the colonies.
Choosing the correct temperatures for school laboratories.
In schools laboratories, we normally incubate bacteria at 25 degrees to prevent harmful bacteria from growing.
If bacteria is kept at a suitable medium, at what rate can they multiply?
Every 20 minutes.
What is the simple process of division called?
Binary Fission.
For what purpose/reason may scientists want to produce cultures of bacteria?
To investigate disinfectants, antibiotics etc.
What useful substances are found in the agar jelly?
These substances help the bacteria to grow.
- Carbohydrates
- Mineral ions
- Extra proteins and minerals
What temperatures is the bacteria culture kept at in Industrial/Laboratories?
60 degrees
What temperatures is the bacteria culture kept at normally?
37 degrees
What temperatures is the bacteria culture kept at in schools?
25 degrees for 48hrs
