Suppose that gene x is induced in e. coli cells when they are treated with high levels of ethanol. a mutation in region 1 in the upstream region of gene x results in high-level expression under basal conditions, and a mutation in region 2 results in an uninducible gene. what would you expect from a strain in which both regions 1 and 2 are mutated?

Because there is a mutation in region one that causes high level expression even in the absence of ethanol, region 1 must bind a transcriptional repressor and regulation of gene X must occur by relief of repression. Since a mutation in gene 2 results in a uninducibility of the gene, region 2 must bind a transcriptional activator. in the absenece of an activator the reprssor becomes irrelevant and the gene is in active regadless of conditions. Mutations in both regions 1 and 2 have the same effect as a single mutation in region 2, because in the absence of a bound transcriptional activator the repressor is irrelaevnat and the gene is inactive regardless of the presence or absence of ethanol

the correct answer, according to e2020, is the second choice there is an occluded front in region a and a cold front in region b.