Question

Penicillin functions as an antimicrobial agent by inhibiting bacterial ___________.

1) cell wall synthesis.
2) folic acid synthesis.
3) protein synthesis.
4) RNA and DNA function.

Answer 1

Penicillin inhibits bacterial cell wall synthesis by targeting the transpeptidase enzyme, causing bacterial cells to burst. Human cells, which contain cell membranes not cell walls, remain unaffected, illustrating the selective toxicity of penicillin.

Step-by-step explanation:

Penicillin functions as an antimicrobial agent by inhibiting bacterial cell wall synthesis. It does this by targeting and inhibiting the enzyme transpeptidase, which is crucial in the final stage of cell wall construction in bacteria. By blocking transpeptidase, penicillin prevents the cross-linking of the peptidoglycan layer, a critical component of bacterial cell walls, leading to defective cell walls and causing bacterial cells to burst due to osmotic pressure. Human cells are unaffected by penicillin because they lack cell walls, instead having cell membranes.

Penicillin and its derivatives, such as penicillin G and V, belong to the class of antibiotics known as β-lactams, named for their active site, the β-lactam ring. The effect of these antibiotics is bactericidal since they cause cell lysis, and due to their selective toxicity, they do not harm human cells. The effectiveness of penicillin is noted in its ability to treat infections caused by Gram-positive bacteria and its expanded spectrum through the development of semisynthetic derivatives.