Question

Which of the following occurs first in transcription?

a.) action of the Rho protein.
b.) formation of a holoenzyme.
c.) formation of an open complex.
d.) formation of a closed complex.
e.) elongation of the mRNA.

Answer 1

The first step in transcription is the formation of a closed complex, where transcription factors and RNA polymerase bind to the promoter region, preceding DNA unwinding and mRNA elongation.

Step-by-step explanation:

The correct answer to the question of which event occurs first in transcription is the formation of a closed complex. Transcription begins with initiation, during which the enzyme RNA polymerase binds to a promoter region on the gene, signaling the DNA to unwind. This allows RNA polymerase to start synthesizing a complementary mRNA molecule. During initiation, several steps occur: First, transcription factors bind to the DNA, followed by the formation of a closed complex where RNA polymerase is bound but the DNA is not yet unwound.

Subsequently, the closed complex transitions to an open complex as the DNA unwinds, and only then does elongation of the mRNA begin. The Rho protein or a hairpin loop in the mRNA leads to termination, which is the final step of transcription. Therefore, the direct answer in two lines is that formation of a closed complex occurs first in transcription before all other events listed.