Bacterial enzymes participate in the construction of the bacterial cell wall. Penicillin targets these enzymes and interferes with:
1. bacterial DNA.
2. the addition of cross-links to the cell wall.
3. protein synthesis.
4. the channels in the cell's internal structure.
Correct Answer: 2
Rationale 1: Penicillin targets the bacteria's cell wall, not its DNA.
Rationale 2: Most penicillins target the enzyme that adds cross-links to the peptidoglycan layers in the cell wall.
Rationale 3: Penicillin targets the bacteria's cell wall, not its protein synthesis.
Rationale 4: Penicillin targets the bacteria's cell wall, not its internal structure.
Global Rationale: Because of the critical importance of their cell walls, bacteria spend a lot of time and energy building them. At least 30 different bacterial enzymes participate in their construction. Some of these enzymes are targets for penicillins and related antibiotics and are called penicillin-binding proteins (PBPs). Most penicillins affect transpeptidase, which is the final PBP enzyme in the construction of the cell wall that adds the cross-links to the peptidoglycan layers. Without the cross-linking, the cell wall becomes weakened and bulges due to the high osmotic pressure inside the cell. The bacterial cell eventually lyses (disintegrates).
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