Culturing microorganisms

Question 1

How often can bacteria divide?

Answer 1

Bacteria multiply by binary fission (a cell division where two identical cells are formed). In the right conditions cells can divide as often as every 20 minutes.

Question 2

How can bacteria be grown in the lab?

Answer 2

Bacteria can be grown in the lab
A culture medium (agar) used containing an energy source (carbohydrate) and minerals.
Petri dishes and agar must be sterilised before use to kill microorganisms.
Inoculating loops used to transfer bacteria after being heated in a Bunsen flame.
The lid of the Petri dish should be sealed with tape to stop other microorganisms getting in (must not be fully sealed so oxygen can get in)
In school, Petri dishes are incubated at 25°C to reduce risk of growth of pathogens that might be harmful to humans.

Question 3

Effectiveness of disinfectants and antibiotics on bacteria experiment

Answer 3

Agar inoculated with BACTERIA.
Paper discs containing antiseptics and antibiotics placed on bacteria and left to grow.
Water disc used as a CONTROL.
If bacteria don’t grow around the disc then the chemical is effective at killing bacteria.
Area where bacteria don’t grow is called ZONE OF INHIBITION.