In eukaryotic cells, transcription cannot begin until (A) the two DNA strands have completely separated and exposed the promoter.

In eukaryotic cells, transcription cannot begin until

(A) the two DNA strands have completely separated and exposed the promoter.

(B) several transcription factors have bound to the

promoter.

(C) the 59 caps are removed from the mRNA.

(D) the DNA introns are removed from the template.

Answer:- The best answer is B. Several transcription factors have bound to the promoter.

Explanation:

Transcription is the process of preparing mRNA from a DNA template. Transcription of genes in eukaryotes does not start until certain transcription factors have joined to the promoter part that is located within the gene. The promoter is a control element located ahead of the transcription initiation point. It has binding sites for RNA polymerase and transcription factors.

Transcription requires several binding transcription factors to the promoter so that RNA polymerase could bind and initiate it. These transcription factors aid in the recruitment and proper alignment of RNA polymerase. They assist in remodeling the chromatin structure to make DNA more accessible. Transcription of all genes requires some transcription factors known as general transcriptions. Others are specific to genes and assist in the regulation of expression for certain genes.

Transcription factors bind the DNA strands causing them to partially unwind close to start site so RNA polymerase can get access of one sugar-phosphate backbone as a template. Answer A is incorrect in that the two strands do not have to separate entirely before transcription may start. Answer C is not right because the 5’ caps are eliminated during RNA processing following transcription. The answer D is wrong because intron’s removal happens during RNA splicing after the initial transcription.

In sum, transcription can only start in eukaryotes after a number of translation factors have bound the promoter region. Their binding leads to the local unwinding of the DNA double helix, causes recruiting RNA polymerase and initiate transcription at start site. This makes B the correct answer.