In eukaryotic cells, how do transcription factors act to control gene expression?

a. they remove introns from pre-mrna.
b. they bind to regulatory regions of dna near the genes.
c. they insert themselves into dna near the beginning of a gene.
d. they code for the synthesis of rna polymerase.

B

Explanation:

They can inhibit or promote RNA polymerase depending on whether it is a repressor or activator respectively.  They bind in the regulatory region on DNA, therefore, this means they will have a DNA-binding domain (DBD). They can physically block the polymerase from transcription or catalyze the acetylation or deacetylation of histone proteins.

/the trachea, commonly known as the windpipe

the sugar-phosphate backbone forms the structural framework of nucleic acids, including dna and rna. this backbone is composed of alternating sugar and phosphate groups, and defines directionality of the molecule.