Case Study 1: The Discovery of Penicillin
In 1928, Dr. Alexander Fleming was investigating the biology of Staphylococcus aureus, a common bacteria on the surface of human skin that causes several diseases. After a summer break away from his lab he returned, only to discover a few culture plates of S. aureus had been contaminated by a blue-green mold. In plates where this mold, Penicillium, was present there were clear areas that contained no bacteria. In culture plates without mold these clear areas were not present (Figure 2).
Given this observation, Fleming hypothesized that the mold must produce a chemical capable of killing S. aureus. To prepare his experiment he first isolated the mold. Dr. Fleming then exposed the mold isolates to a new culture of S. aureus. After exposure, Fleming observed that all the bacteria in the new culture died. Having identified this as an anti-bacterial chemical, Fleming named the substance penicillin. However, it would take another decade before penicillin could be fully developed into the wonder drug it came to be known as.
1a. What was Dr. Fleming investigating?,
1b. What was Dr. Fleming’s hypothesis?,
1c. Rewrite Dr. Fleming’s prediction using the if/then format.,
1d. What was the independent variable for this experiment? What was the dependent variable?,
1e. Do the results indicate that the hypothesis should be rejected or retained? Explain your reasoning.,
Case Study 1: The Discovery of Penicillin
In 1928, Dr. Alexander Fleming was investigating the biology of Staphylococcus aureus, a common bacteria on the surface of human skin that causes several diseases. After a summer break away from his lab he returned, only to discover a few culture plates of S. aureus had been contaminated by a blue-green mold. In plates where this mold, Penicillium, was present there were clear areas that contained no bacteria. In culture plates without mold these clear areas were not present (Figure 2).
Given this observation, Fleming hypothesized that the mold must produce a chemical capable of killing S. aureus. To prepare his experiment he first isolated the mold. Dr. Fleming then exposed the mold isolates to a new culture of S. aureus. After exposure, Fleming observed that all the bacteria in the new culture died. Having identified this as an anti-bacterial chemical, Fleming named the substance penicillin. However, it would take another decade before penicillin could be fully developed into the wonder drug it came to be known as.
1a. What was Dr. Fleming investigating?
1b. What was Dr. Fleming’s hypothesis?
1c. Rewrite Dr. Fleming’s prediction using the if/then format.
1d. What was the independent variable for this experiment? What was the dependent variable?
1e. Do the results indicate that the hypothesis should be rejected or retained? Explain your reasoning.