Why are most Gram-negative bacteria resistant to the actions of penicillin View Available Hint(s) Penicillin is unable to pass through the thick layer of peptidoglycan. Penicillin is unable to pass through the outer membrane of the cell wall. Penicillin is unable to pass through the teichoic acid barrier. Gram-negative bacteria lack a peptidoglycan cell wall. Submit

Most Gram-negative bacteria resist penicillin due to their unique cell wall structure, which includes an outer membrane that acts as a barrier to many substances, including certain antibiotics. This outer membrane is composed of lipopolysaccharides and proteins, making it impermeable to penicillin, which hinders the drug's ability to target the peptidoglycan layer underneath effectively. Additionally, Gram-negative bacteria have a relatively thin layer of peptidoglycan compared to Gram-positive bacteria, but this layer is supplemented by the outer membrane. This combination not only physically blocks penicillin but also often leads Gram-negative bacteria to produce enzymes called beta-lactamases, which can actively break down penicillin before it has a chance to work.