Question

In the first step of their experiments, Jacob and Monod treated E. coli cells with ultraviolet light or X-rays to ________.

A) decrease the rate of gene expression
B) induce DNA repair enzymes
C) increase the frequency of mutations in all genes
D) selectively mutate the lac operon, leaving all other genes unmutated

Answer 1

C) increase the frequency of mutations in all genes

Step-by-step explanation:

François Jacob and Jacques Monod carried out a series of experiments during their studies on the regulation of gene expression in E. coli. They exposed the E. coli cells with ultraviolet light or X-rays to allow mutations in all the genes to investigate the nature of enzyme synthesis in E. coli. They observed that some enzymes are synthesized continuously. They called those enzymes the constitutive enzymes. On the other hand, some enzymes were synthesized only when required by the cell.

Their further experiments included selective mutation of specific regulatory genes to observe the effect on the expression of other genes.