Experiment Method of How Dr Alexander Fleming Discovered Penicillin
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You must have heard about penicillin the wonder drug that cures many bacterial diseases. This drug was accidentally discovered by Sir Alexander Fleming while he was studying the growth of a certain type of bacterium.
Step 1: Fleming was studying the growth and reproduction of the bacterium Staphylococcus is dishes containing agar to which nutrients had been added.
Step 2: He observed that a mould Penicillium was also growing in some of the dishes. (The mould had got the dishes by accident) In addition, he observed a clear zone around the area where the mould grew, indicating that the bacteria growing there had died.
Step 3: What had caused the bacteria to die?
Step 4: Fleming put forward a hypothesis: the mould produced a chemical which diffused into the surrounding agar and killed the bacteria.
Step 5: To test his hypothesis he designed an experiment. He grew the mould in a liquid nutrient broth so that the chemical it produced would diffuse into the broth. He added some of this broth minus the mould to the bacteria.
Step 6: He observed that the bacteria died after broth was added.
Step 7: Was there something in the nutrient broth that caused the bacteria to die?
Step 8: To find out the answer to this question; he added some nutrient broth in which no mould had been grown to the bacteria.
Step 9: The bacteria did not die.
Step 10: The confirmed that Fleming’s hypothesis was correct. It was tested by other scientists. The chemical was isolated and named penicillin.
Below is how Fleming made his discovery.
Step 1: Fleming was studying the growth and reproduction of the bacterium Staphylococcus is dishes containing agar to which nutrients had been added.
Step 2: He observed that a mould Penicillium was also growing in some of the dishes. (The mould had got the dishes by accident) In addition, he observed a clear zone around the area where the mould grew, indicating that the bacteria growing there had died.
Step 3: What had caused the bacteria to die?
Step 4: Fleming put forward a hypothesis: the mould produced a chemical which diffused into the surrounding agar and killed the bacteria.
Step 5: To test his hypothesis he designed an experiment. He grew the mould in a liquid nutrient broth so that the chemical it produced would diffuse into the broth. He added some of this broth minus the mould to the bacteria.
Step 6: He observed that the bacteria died after broth was added.
Step 7: Was there something in the nutrient broth that caused the bacteria to die?
Step 8: To find out the answer to this question; he added some nutrient broth in which no mould had been grown to the bacteria.
Step 9: The bacteria did not die.
Step 10: The confirmed that Fleming’s hypothesis was correct. It was tested by other scientists. The chemical was isolated and named penicillin.
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