Q5.9. Suppose a drug blocked the entry of tRNA molecules into the ribosome. What effect would this drug have on gene expression? There would be no effect, because tRNA is not part of the product of gene expression (i.e., is not a polypeptide). Transcription initiation would be blocked, so the cell would be unable to synthesize mRNA and polypeptides. Translation elongation would be blocked, so the cell would be unable to synthesize polypeptides. Translation termination would be blocked, so the ribosome would remain attached to the polypeptide.