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Regulation of gene expression and cell specialization


The trp operon in E. Coli is a coordinately controlled set of genes involved in tryptophan biosynthesis. Tryptophan acts as a corepressor of the operon, which means it binds to and activates the trp repressor protein. This binding is more likely to occur when tryptophan is present at high levels in the cell.
The following diagram represents the genes and regulatory sequences of the trp operon.
The following symbols represent the macromolecules involved in transcriptional regulation of the trp operon.
Which of the following diagrams best models the regulation of the trp operon when tryptophan is present at high levels?
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