What does penicillin primarily disrupt in bacterial cells?

Penicillin primarily disrupts cell wall synthesis in bacterial cells. This antibiotic belongs to the class of beta-lactam antibiotics, which specifically target the synthesis of peptidoglycan, an essential component of the bacterial cell wall. By inhibiting enzymes known as penicillin-binding proteins (PBPs), penicillin disrupts the cross-linking of the peptidoglycan layers, which is crucial for maintaining cell wall strength and integrity.

As a result, bacteria under the influence of penicillin cannot properly form their cell walls, leading to cell lysis, especially in hypotonic environments where osmotic pressure can cause the bacteria to burst. This mechanism is particularly effective against Gram-positive bacteria, which rely heavily on their thick peptidoglycan walls.

The other options involve processes that are not the primary target of penicillin. While protein synthesis and ribosome function are vital for bacterial growth and reproduction, they are not specifically disrupted by penicillin. Similarly, membrane integrity is important for cell survival, but penicillin does not act directly on the bacterial membrane; rather, its primary action is on the cell wall. This specificity makes penicillin a crucial antibiotic in the treatment of bacterial infections.