Question

If the transcription of the trp operon is regulated by the action of the repressor (TrpR) only, we would expect a trpR- mutant to ______.

a) Overexpress the trp operon genes
b) Underexpress the trp operon genes
c) Induce the trp operon genes
d) Repress the trp operon genes

Answer 1

In the case of a trpR- mutant, which lacks a functional repressor for the trp operon, we would expect the trp operon genes to be overexpressed due to the loss of repression.

Step-by-step explanation:

In prokaryotic cells, operons are often regulated by repressors that can turn off the expression of genes within the operon. The trp operon is a classic example of such regulation, where the TrpR repressor protein binds to the operator to prevent transcription when tryptophan levels are high. If the cell has a trpR- mutation, meaning the repressor protein is not functional, the trp operon would not be properly regulated. In such a case, without the repressor available to turn off the operon, we would expect the cell to overexpress the trp operon genes.