Gene Expression and Regulation Question 7

The figure above depicts the DNA-protein complex that is assembled at the transcriptional start site of gene $X$ when the expression of gene $X$ is activated in liver cells. Previous studies have shown that gene $X$ is never expressed in nerve cells. Based on the diagram, which of the following most likely contributes to the specific expression pattern of gene $X$ ?

Expression of gene

X

produces large amounts of tRNA but undetectable amounts of mRNA.

The general transcription factors inhibit the activation of gene

X

in liver cells by blocking the activator from binding to RNA polymerase II.

The activator is a sequence-specific DNA-binding protein that is present in some tissues but not in other tissues.

The enhancer is a unique DNA segment that is added to the nuclear DNA of some cells of an organism during the process of mitotic cell division but not other cells.