Aresearcher is studying gene expression in different types of cells. for a gene of interest, he notes its expression no longer appears to be regulated it occurs in all cells, rather than in just a few cell types. the gene’s corresponding transcript and protein, however, appear normal. this may be the result of a mutation in which of the following regions associated with the gene? a) exonb) intronc) promoterd) silencer

The correct answer is option d) "Silencer".

Explanation:

Gene silencing is the regulation of a gene expression that results in avoiding the expression of a gene during a certain period of time. A silencer is a DNA sequence that produces gene silencing. In this example the researcher founds that a gene is not longer regulated in all cells and the gene is still transcribed and translated into protein. The mutation responsible of this it is likely to be occurring in a silencer, avoiding gene silencing of the studied gene in all cells.

you know they are heterozygous for a trait because they have it as jj or jj.