Which of the following statements is/are true about the trp operon? Select ALL answer choices that apply.

Question

BlackTom AI · Accepted Answer

Question restatement: The task asks which statements about the trp operon are true, and it is a 'select all that apply' type with two given options.
Option 1: 'Tryptophan binds to the trp repressor and causes a conformational change that allows the repressor to bind to the operator, thereby stopping transcription.' This reflects the classic mechanism of the trp operon: tryptophan acts as a corepressor, binding to the aporepressor and inducing a shape change that enables the repressor to bind the operator region. Once bound, RNA polymerase is blocked from effectively initiating transcription of the trp operon genes. Therefore, this statement accurately describes the repressor-operator interaction and transcriptional attenuation under high tryptophan levels.
Option 2: 'The trp operon is repressed by the presence of tryptophan.' This is a concise summary of the same core idea: when tryptophan is abundant, it serves as a corepressor to inhibit transcription by enabling repressor binding to the operator. The operon is indeed repressed in the presence of tryptophan, aligning with the feedback inhibition model controlling tryptophan biosynthesis genes.
Why Option 1 and Option 2 are correct, in short: both statements capture the same regulatory mechanism from two perspectives—the molecular event (tryptophan-activated repressor-operator binding) and the overall outcome (repression of transcription). The central concept is that tryptophan availability modulates repressor activity to prevent unnecessary production of tryptophan when it is plentiful.
Why other potential misconceptions would be wrong (addressing alternatives not listed here): If one were to claim that tryptophan never binds the repressor or that transcription proceeds regardless of tryptophan levels, those would contradict established operon regulation principles. If one suggested that repression occurs only in the absence of tryptophan, that would be incorrect for the trp operon, which uses tryptophan as a corepressor to turn repression on when tryptophan is plentiful.
Overall assessment: Both provided statements are consistent with the canonical model of the trp operon regulation by tryptophan acting as a corepressor, leading to repressor binding at the operator and transcriptional repression.

BIOL_1105_60452_202506 Lesson 14 Homework

Which of the following statements is/are true about the trp operon? Select ALL answer choices that apply.

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