Which factor$(s)$ participate in the process of transcription in prokaryotes?

During transcription,the holoenzyme $RNA$ polymerase binds to the $DNA$ strand. It forms a structure resembling a saddle at a specific site on the $DNA$. This sequence is called .....

Which form of $RNA$ is most heterogeneous?

Define a cistron. Giving examples,differentiate between monocistronic and polycistronic transcription units.

Given below are two statements, one is labelled Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A) :$ In eukaryotes, primary transcripts $(hnRNA)$ contain both exons and introns, and introns are non-functional.
Reason $(R) :$ In bacteria, the $mRNA$ does not require any processing, and transcription and translation take place in the same compartment.
In the light of the above statements, choose the most appropriate answer from the options given below $:$

Which of the following is not a part of a transcription unit?