Which of the following statements is true of the attenuation mechanism used to regulate the tryptophan biosynthetic operon in E.coli?

Question

Quizplus · Accepted Answer

The attenuation mechanism involves the regulation of transcription of the trp operon in response to tryptophan levels in the cell. The leader peptide gene, which precedes the structural genes in the trp operon, contains trp codons that allow the system to monitor cellular tryptophan levels. When tryptophan levels are high, the ribosome stalls at these trp codons, allowing a stem-loop structure to form in the mRNA. This stem-loop structure then causes premature termination of transcription, leading to attenuation of the operon. Conversely, when tryptophan levels are low, the ribosome is able to efficiently translate the leader peptide, preventing the stem-loop structure from forming and allowing transcription of the structural genes to proceed.

Which of the Following Statements Is True of the Attenuation