The antibiotic that inhibits protein synthesis by premature termination and which structurally resembles amino acyl t–RNA is :
## **Core Concept**
The question tests understanding of antibiotic mechanisms, specifically those inhibiting protein synthesis. It requires knowledge of how certain antibiotics structurally mimic aminoacyl-tRNA, leading to premature termination of protein synthesis.
## **Why the Correct Answer is Right**
The correct answer, **C. Puromycin**, works by mimicking the structure of aminoacyl-tRNA. During protein synthesis, puromycin is incorporated into the growing peptide chain, causing premature termination. This is because puromycin has a similar structure to the 3' end of aminoacyl-tRNA, allowing it to be accepted by the ribosome and incorporated into the peptide chain.
## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because, although some antibiotics inhibit protein synthesis, there's no information provided to directly link it with mimicking aminoacyl-tRNA and causing premature termination.
- **Option B:** This option is incorrect as it does not match the mechanism described; it might act through a different pathway or not effectively mimic aminoacyl-tRNA.
- **Option D:** This option is incorrect because it does not structurally resemble aminoacyl-tRNA or cause premature termination through the described mechanism.
## **Clinical Pearl / High-Yield Fact**
A key point to remember is that **puromycin** is an antibiotic that acts by inhibiting protein synthesis through a mechanism that involves mimicking aminoacyl-tRNA, leading to premature chain termination. This action is notably different from other protein synthesis inhibitors and is a classic example in pharmacology.
## **Correct Answer: C. Puromycin**