Which of the following drug acts at 50s ribosome:
**Question:** Which of the following drugs acts at 50s ribosome?
**Core Concept:**
The ribosome is a complex cellular structure involved in protein synthesis. It is composed of ribosomal RNA (rRNA) and ribosomal proteins. Proteins are synthesized in cells through a process called translation, which occurs in three main steps: initiation, elongation, and termination. The 50s ribosome is a subunit of the larger 70s ribosome, which is responsible for the elongation step of protein synthesis.
**Why the Correct Answer is Right:**
The correct answer, D-tobramycin, is an aminoglycoside antibiotic that primarily targets bacteria. Aminoglycosides act by binding to specific sites on the 16S rRNA, a component of the 30S ribosomal subunit, which is part of the 70S ribosome. This binding interferes with the elongation step of protein synthesis, preventing the accurate joining of amino acids and leading to the inhibition of bacterial growth.
**Why Each Wrong Option is Incorrect:**
A. Streptomycin is another aminoglycoside antibiotic that acts on the 16S rRNA, like tobramycin, but it is not specific to the 50S ribosome subunit, making it incorrect.
B. Gentamicin is another aminoglycoside antibiotic that acts on 16S rRNA, similar to tobramycin and streptomycin, but it is not specific to the 50S ribosome subunit, making it incorrect.
C. Streptothricin is not an aminoglycoside antibiotic, making it irrelevant to the question.
**Clinical Pearl:**
Understanding the pharmacodynamics of aminoglycoside antibiotics is crucial when treating infections caused by Gram-negative bacteria, as they are often resistant to beta-lactam antibiotics. Selecting the appropriate aminoglycoside based on the patient's infection site and severity is essential for effective treatment.