Antibiotics
Antibiotics are used to treat bacterial infections.
Antibiotics aren鈥檛 as specific as antibodyA chemical produced by a lymphocyte in response to an antigen., meaning an antibiotic can be used to treat more than one type of bacterial infection.
Practical 2.3
Investigate the effect of different chemicals on the growth of bacteria
Procedure
- aseptic techniquesName given to the laboratory procedures carried out to prevent the contamination of pure cultures of microorganisms. needs to be followed during this procedure
- Make different plant extracts (grind plant leaves and water using a pestle and mortar).
- Soak a small filter paper disc in each plant extract.
- Add bacteria to a Petri dish using a sterile spreader.
- Place the discs as far from each other as possible on the bacteria in the Petri dish.
- Tape down the Petri dishA clear glass or plastic dish, used to grow living cells from organisms so they can be studied. lid.
- Invert (turn upside down) to prevent condensation dripping on the bacteria.
- incubateTo keep a sample of microbes warm so that the cells reproduce quickly. at 25掳C for 2-3 days.
- Measure the radius/diameter of any clear zones around the discs.
Results
The larger the clear zone the more effective the antibacterial substance is at killing or preventing bacterial growth.