Final answer:
The correct answer to the question is option 'A'. Ampicillin, amoxicillin, mezlocillin, and penicillin G all target the bacterial cell wall as part of their mechanism to combat infections. They inhibit bacterial growth by preventing the synthesis of the cell wall.
Step-by-step explanation:
Ampicillin, amoxicillin, mezlocillin, and penicillin G all target the cell wall. These antibiotics are part of a group known as ß-lactams, which includes the penicillins, cephalosporins, carbapenems, and monobactams. They exert their bactericidal action by inhibiting the synthesis of the bacterial cell wall. Specifically, they prevent the cross-linking of peptides on the mucopolysaccharide chains, which is essential for cell wall integrity. Without properly formed cell walls, bacteria cannot prevent the influx of water and burst due to osmotic pressure.
While these antibiotics are effective against certain Gram-positive and some Gram-negative bacteria, they can differ in terms of their spectrum of activity and resistance to ß-lactamase enzymes. For example, ampicillin and amoxicillin are broad-spectrum aminopenicillins, while penicillin G is not orally administered because it is unstable in the acidic environment of the stomach. Methicillin was developed to be resistant to penicillinase, an enzyme that can deactivate penicillins.
Answering the question above, the correct option would be 'A' as all these antibiotics target the cell wall. They are not all semisynthetic, do not all have resistance to the action of penicillinase, nor do they all have an expanded spectrum of activity. However, some modifications in the R groups of these penicillins have been made to create semisynthetic versions with these characteristics.