Penicillin was first introduced as an antibiotic in the early 1940s. Since that time, it has been found to be effective against the bacteria that cause gonorrhea, a sexually transmitted disease. The drug acts on dividing bacterial cells by preventing the formation of a new protective cell wall. Without the wall, the bacteria can be killed by normal body defenses. Recently, a new strain of this disease-causing bacterium has been found. This particular bacterium produces an enzyme that metabolizes penicillin. How can gonorrhea be controlled now that this organism is resistant to penicillin? How did a resistant strain develop? Include the following in your consideration: DNA, enzymes, selecting agents, and gene-frequency changes.

Are there other antibiotics that kill or interfere with the ability of the gonorrhea bacterium's ability to reproduce? How are enzymes produced? What molecule determines the kinds of enzymes produced? In the case of the gonorrhea bacterium, what is acting as a selecting agent? How has the frequency of the gene that metabolizes penicillin changed? Why did it change?