Based on the information you know about the trp operon, is the creation of tryptophan expensive to the cell?

• A. Yes, this is why tryptophan is the co-repressor of the trp operon.
• B. No, this is why tryptophan is the inducer of the trp operon.
• C. Yes, this is why tryptophan is the repressor of the trp operon.

Answer: (A)

Verified step by step guidance

1. Understand the role of the trp operon: The trp operon is a group of genes that are used to produce tryptophan when it is not available in the environment. It is regulated by the presence of tryptophan itself.
2. Identify the function of tryptophan in the trp operon: Tryptophan acts as a co-repressor, meaning it binds to the repressor protein, enabling it to attach to the operator region of the operon and inhibit transcription.
3. Consider the energy cost of synthesizing tryptophan: The synthesis of tryptophan requires energy and resources, making it an expensive process for the cell.
4. Analyze why tryptophan acts as a co-repressor: When tryptophan levels are high, it binds to the repressor, preventing the operon from producing more tryptophan, thus conserving energy and resources.
5. Conclude the relationship between tryptophan and the trp operon: The presence of tryptophan as a co-repressor indicates that its synthesis is costly, and the cell regulates its production to avoid unnecessary expenditure.