Question

What are the roles of allolactose in the lac operon and tryptophan in the trp operon?

Answer 1

What are the roles of allolactose in the lac operon and tryptophan in the trp operon?

The function of allolactose in regulation of the lac operon is that the allolactose acts as an inducer. Tryptophan acts as a corepressor that causes the trp repressor to bind to the trp operon and repress transcription.

Answer: A) allolactose acts as an inducer and tryptophan acts as a corepressor.

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Answer 2

The answer is allolactose is an inducer while tryptophan is corepressor in the trp operon.

The trp operon is a group of genes transcribed together that code for the synthesis of tryptophan (trp). It is present in many bacteria.
In the trp operon, allolactose binds to and deactivates Lacl. Since LacI is the repressor of the lac operon genes, its deactivation allows the lac operon transcription. Therefore, allolactose is the inducer.
In the trp operon, tryptophan binds to and activates TrpR. Since TrpR is the repressor of the trp operon, its activation stops the trp operon transcription. Therefore, tryptophan is the repressor.