Practice question

Attenuation in trp operon depends on coupling between transcription and translation through leader peptide messenger that contains regulatory RNA segments capable of forming alternative mutually exclusive hairpin structures. As RNA polymerase transcribes 162-nucleotide leader region, ribosome immediately engages nascent transcript translating 14-codon leader peptide sequence. Instantaneous rate of ribosome movement at twin Trp codons within region one dictates which RNA secondary structures can form downstream among regions two three four. This precise translational sensing allows cell to continuously monitor charged Trp-tRNA levels and adjust elongating polymerase behavior accordingly, integrating metabolic nutritional status directly into transcriptional readthrough decision at attenuator.