Unit 4.1.1.6 Triple Culturing Microorganisms Flashcards
What are bacteria grown in?
culture medium
What does the culture medium contain?
carbohydrates, minerals, proteins, vitamins
What are bacteria grown on?
agar plates
Bacteria grow on the agar plate and form visible…
colonies
Agar plates are incubated at what temperature?
25 degrees
In industrial conditions agar plates are incubated at higher temperatures because
they can grow faster
Why are schools not allowed to incubate plates at high temperatures?
encourages growth of harmful microorganisms
Name substances that can kill bacteria
antiseptics, antibiotics
When growing bacteria on agar plates, discs of antibiotic can be added. What is the area around the disc called where no bacteria is growing?
zone of inhibition
Discs soaked in antibiotic and placed on the agar plate, enter the plate by what process?
diffusion
Which bacteria are NOT killed by the antibiotic?
antibiotic resistant bacteria
When investigating bacterial growth with different antibiotics what should the control disc contain?
disc soaked in water
When investigating bacterial growth why is a control important?
to be sure that any difference in growth is due to the antibiotic only
bacteria reproduce by what process
binary fission
How can you prevent unwanted microorganisms from growing on your agar plate?
use sterile petri dishes sterilise the inoculating loop sterilise the culture medium before adding your bacteria tape the lid on
What is the purpose of taping the agar lid on?
to prevent unwanted microorganisms from entering
How do you sterilise an inoculating loop?
pass it through a hot flame
what does sterilise mean?
to kill unwanted microorganisms
An example of a prokaryotic cell is
bacteria
What happens to the bacterial cell when it divides by binary fission
it splits into 2
A bacterial cell has a mean division time of 30 minutes. How many cells will there be after 2.5h?
5 divisions 2 to the power 5 = 32 cells
What is the mean division time of a bacterial cell?
the time it takes to divide into 2
What conditions are required for bacterial growth?
warmth, oxygen, moisture and an energy source (carbohydrates)
How is bacterial DNA different to animal cell DNA?
bacterial cells have.. No nucleus free floating in cytoplasm circular portions called plasmids
Why do you store agar plates in an incubator upside down?
to prevent condensation landing on the bacterial lawn and disturbing it
How can you tell which antibiotic disc is the most effective?
It has a bigger zone of inhibition
How do you calculate the area of the zone of inhibition?
use the formula for area of a circle (pie r squared)
What process is this diagram representing?
Binary fission
