Which of the following antibiotic does not act by inhibiting protein synthesis ?
## **Core Concept**
The question tests understanding of antibiotic mechanisms of action, specifically those that inhibit protein synthesis. Protein synthesis inhibitors are a class of antibiotics that work by interfering with the bacterial cell's ability to produce proteins, which are essential for various cellular functions.
## **Why the Correct Answer is Right**
acts by inhibiting cell wall synthesis, not protein synthesis. It is a beta-lactam antibiotic that interferes with the bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs) located inside the bacterial cell wall. This action results in the weakening of the cell wall and ultimately leads to cell lysis and death. Therefore, it does not act by inhibiting protein synthesis.
## **Why Each Wrong Option is Incorrect**
* **Option A:** is incorrect because acts by inhibiting protein synthesis. It binds to the 30S subunit of the bacterial ribosome, interfering with the initiation complex of peptide formation, which leads to misreading of mRNA.
* **Option B:** is incorrect because also inhibits protein synthesis. It binds to the 50S subunit of the bacterial ribosome and inhibits peptide bond formation.
* **Option D:** is incorrect because inhibits protein synthesis as well. It binds to the 30S ribosomal subunit and causes misreading of mRNA, leading to incorporation of incorrect amino acids into proteins.
## **Clinical Pearl / High-Yield Fact**
A key point to remember is that different classes of antibiotics have distinct mechanisms of action:
- **Inhibitors of cell wall synthesis**: ,
- **Inhibitors of protein synthesis**: , ,
- **Inhibitors of nucleic acid synthesis**: Fluoroquinolones
- **Interferers with cell membrane function**: Polymyxins
## **Correct Answer: .**