Question

Two types of mutations in the gene encoding phosphoribosylpyrophosphate synthetase, or PRS, have been observed. One mutation alters the regulatory site on the enzyme, whereas the other mutation alters the promoter of the enzyme. Both mutations result in increased PRS activity. How will the two different mutations in PRS affect the transition between the R and T states of the enzyme? The mutation in the regulatory site will not affect the transition between the R and T states. The mutation in the promoter will prevent PRS from switching to the T state. The mutation in the regulatory site will prevent PRS from switching to the T state. The mutation in the promoter will not affect the transition between the R and T states. Neither mutation will affect transition between the R and T states of the enzyme. The mutation in the regulatory site will prevent PRS from switching to the state. The mutation in the promoter will prevent PRS from switching to the T state.

Answer 1

The correct option is

The mutation in the regulatory site will prevent PRS from switching to the T state. The mutation in the promoter will not affect the transition between R and T states.

Explanation:

Out of the two mutations that are observed, one of them is in the promoter of the enzyme. This mutation is outside the gene of the enzyme and therefore does not lead to any change in the aminoacid sequence of the enzyme. Therefore the enzyme produced in this mutation will not show any difference in transition between R & T states as compared to the wildtype enyzyme. The observed effect of increased PRS activity is possible because this mutation can increase the expression level of the PRS gene ( promoter of a gene controls the expression level of that gene).