Question

Penicillin is an enzyme-inhibiting antibiotic that kills bacteria by suppressing the synthesis of bacterial cell walls. The bacterial cell wall is made of cross-linked peptidoglycan, which is synthesized from peptidoglycan monomers by transpeptidase enzymes. How does penicillin suppress the synthesis of bacterial cell walls? O Penicillin binds to the cross-linked peptidoglycan, preventing further bacterial cell wall growth. Penicillin signals the bacterial cell to stop producing the transpeptidase enzymes. Penicillin binds to the transpeptidase enzymes, preventing the synthesis of cross-linked peptidoglycan. Penicillin binds to the peptidoglycan monomers, preventing their conversion to cross-linked peptidoglycan.

Answer 1

Answer: Penicillin binds the transpeptidase enzyme, preventing the synthesis of cross linked peptidoglycan.

Explanation: The important characteristic in the structure of penicillin is beta-lactam ring as it is responsible for penicillin’s antibacterial property. In case of Gram positive bacteria the cross linking between the peptidoglycan is brought about by the action of transpeptidase enzyme for formation of cell wall. Penicillin’s beta-lactam ring binds to the transpeptidase enzyme and inhibits its activity resulting in cell wall not being formed. The cell in absence of cell wall becomes vulnerable and dies. Since the action of penicillin takes place during cell wall formation, the bacterial cell in the growth phase or log phase are the most vulnerable to its action.

Note penicillin is not able to act on Gram negative organisms as these bacteria have a outer wall made up of lipopolysaccharide and protein layer and the peptidoglycan layer is inside,so penicillin can not reach the peptidoglycan layer.