What is the likely effect of each of the following mutations of the trpL region on attenuation control of trp operon gene transcription? Explain your reasoning.

Region 3 is deleted.

Verified step by step guidance

1. <span>Understand the role of the trpL region in the trp operon. The trpL region contains sequences that can form stem-loop structures, which are crucial for the attenuation mechanism controlling the transcription of the trp operon.</span>
2. <span>Identify the specific regions within the trpL leader sequence. The leader sequence contains four regions (1, 2, 3, and 4) that can form different stem-loop structures: 1-2, 2-3, and 3-4.</span>
3. <span>Recognize the function of the 3-4 stem-loop structure. The 3-4 stem-loop acts as a transcription terminator, halting transcription when tryptophan levels are high.</span>
4. <span>Analyze the effect of deleting region 3. Without region 3, the 3-4 terminator cannot form, potentially leading to continuous transcription of the trp operon regardless of tryptophan levels.</span>
5. <span>Conclude the likely outcome. The deletion of region 3 would likely result in the loss of attenuation control, causing the trp operon to be transcribed even when tryptophan is abundant, as the termination signal is disrupted.</span>

Key Concepts

Attenuation Control

Attenuation control is a regulatory mechanism in prokaryotes, particularly in the trp operon, that modulates gene expression based on the availability of tryptophan. It involves the formation of specific RNA structures during transcription that can either promote or inhibit the continuation of transcription. This process allows the cell to respond quickly to changes in nutrient availability, ensuring efficient resource use.

trp Operon

The trp operon is a cluster of genes in bacteria that encode enzymes necessary for the biosynthesis of the amino acid tryptophan. It is regulated by both repression and attenuation mechanisms, allowing the cell to adjust the production of tryptophan based on its concentration. The operon consists of structural genes, a promoter, and regulatory sequences that control transcription.

RNA Secondary Structure

RNA secondary structure refers to the specific folding of RNA molecules into shapes that are stabilized by base pairing. In the context of the trp operon, the formation of alternative structures in the leader region (trpL) determines whether transcription will continue or terminate. Deletion of region 3 can disrupt these structures, potentially affecting the ability of the RNA to form the necessary hairpin loops that signal attenuation.