Enhancers __________.

In a eukaryote, transcription factors called activators may stimulate gene expression by binding to DNA sites called __________.

Dioxin, produced as a by-product of various industrial chemical processes, is suspected of causing cancer and birth defects in animals and humans. It apparently acts by entering cells and binding to specific proteins, which then enter the nucleus and alter the pattern of gene expression. Therefore, dioxin acts by mimicking the action of __________.

A high rate of gene transcription in eukaryotic cells is usually dependent on __________.

MyoD promotes muscle cell development by __________.

Which of these statements about enhancers is correct?a. They contain a unique base sequence called a TATA box.b. They are located only in 5′ untranslated regions.c. They are located only in introns.d. They are found both upstream and downstream from the transcription start site and are functional in any orientation.