Final answer:
Tetracyclines act as a bacteriostatic agent by binding to the 30S subunit of bacterial ribosomes and blocking the binding of tRNA, which inhibits bacterial protein synthesis without affecting eukaryotic cells.
Step-by-step explanation:
The mechanism of antibacterial action of tetracyclines involves inhibiting bacterial protein synthesis by blocking the attachment of transfer RNA (tRNA) to the ribosome. More specifically, tetracyclines bind to the 30S ribosomal subunit and prevent tRNA-amino acid complexes from associating with the ribosome, which is essential for protein synthesis. Although tetracyclines can inhibit protein synthesis in the host, they are less likely to affect eukaryotic cells because these cells lack a tetracycline uptake mechanism. This selective targeting allows tetracyclines, which are a natural antibiotic produced by soil bacteria, to halt bacterial protein synthesis without harming the patient, acting as a bacteriostatic agent.