Inhibitors Affecting Molecular Processes

The question asks to identify the cellular process inhibited by Diphtheria toxin, tetracycline, and streptomycin.

Mechanism of Action Analysis

• Diphtheria toxin functions by inactivating elongation factor 2 (eEF2) through ADP-ribosylation. This step is crucial for the movement of the ribosome along the mRNA during protein synthesis.
• Tetracycline binds to the 30S ribosomal subunit, preventing the binding of aminoacyl-tRNA to the A (acceptor) site. This directly blocks the addition of new amino acids to the growing polypeptide chain.
• Streptomycin, another antibiotic targeting the 30S ribosomal subunit, interferes with the initiation complex formation and causes misreading of the mRNA codons. This leads to the production of non-functional proteins.

Target Process Identification

All three agents—Diphtheria toxin, tetracycline, and streptomycin—specifically interfere with the process of translation, which is the synthesis of proteins from an mRNA template. They target different aspects of this process, including elongation, aminoacyl-tRNA binding, and fidelity of codon reading.

Conclusion

Therefore, Diphtheria toxin, tetracycline, and streptomycin inhibit translation.