The translation of mRNA into polypeptides is carried out by ribosomes in both pr
ID: 176884 • Letter: T
Question
The translation of mRNA into polypeptides is carried out by ribosomes in both prokaryotic and eukaryotic cells. There are several key differences between prokaryotic and eukaryotic ribosomes which have been exploited by some antibiotics to selectively target bacterial ribosomes. Select the best description of how each antibiotic inhibits translation. eptomycin is an amino glycoside. It binds to the 16S rRNA which interferes with the proofreading function of the 30S subunit. Tetracycline's bind to and distort the A site. Puromycin has a structure similar to the 3' end of an aminoacyl-tRNA. It binds to the A site and reacts with the peptidyl-tRNA to form peptidylpuromycin which cannot be translocated to the P site, and has a weak affinity for the A site. Azithromycin is a macrolide. It binds to 50S subunit and interferes with the exit of the growing polypeptide chain from the ribosome.Explanation / Answer
Strptomycin: Streptomycin inhibits the translocation step by binding to the small subunit ribosomal RNA and blocking the activity of EF-G. It prevents elongation of translation procedure.
Tetracyclines: Tetracyclines inhibit bacterial protein synthesis by preventing the association of aminoacyl-tRNA with the bacterial ribosome. It prevents initiation of translation procedure.
Puromycin: Puromycin is an aminonucleoside antibiotic that causes premature chain termination during translation taking place in the ribosome. It enters the A site and transfers to the growing chain, causing the formation of a puromycylate nascent chain and premature chain release. It prevents termination.
Azithromycin: Azithromycin prevents bacteria from growing by interfering with their protein synthesis. It binds to the 50S subunit of bacterial ribosome, and inhibiting translation of mRNA. It prevents initiation.
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