Which cellular structure is targeted by penicillin in bacteria?

The correct answer is the cell wall. Penicillin specifically targets the synthesis of the bacterial cell wall, which is composed primarily of peptidoglycan. This antibiotic interferes with the enzymes responsible for cross-linking the peptide chains in the peptidoglycan layer, which is essential for maintaining the structural integrity of the bacterial cell wall. As a result, bacteria become unable to properly form their cell walls, leading to cell lysis and death, particularly during cell division when the demand for a robust cell wall is critical.

The importance of the cell wall is particularly pronounced in Gram-positive bacteria, which have a thick peptidoglycan layer. When penicillin disrupts the formation of this layer, the bacteria are unable to withstand osmotic pressure, causing them to burst.

Other structures mentioned, like the cytoplasmic membrane and the plasma membrane, play roles in cellular processes and maintaining homeostasis, but they are not the specific targets of penicillin. Similarly, while ribosomes are essential for protein synthesis, penicillin does not affect this process directly; instead, antibiotics like tetracycline and erythromycin target ribosomes. Understanding the specific action of penicillin on the bacterial cell wall is crucial for comprehending its mechanism as an antibacterial agent