Question

Explain transcription. A transcription unit in DNA is defined primarily by three regions. Write the names of any two regions.

Answer 1

A transcription step is called the extension of DNA transcribed to an RNA molecule and encodes at only one gene. The transcription generates messenger RNA (mRNA) unless the gene encodes a protein; the mRNA, in essence, acts as a guide for the synthesis of the protein by translation.

Complete answer:
First we should know about transcription to answer this question.Transcription is the first of many DNA-based gene expression phases in which the enzyme RNA polymerase copies a specific segment of DNA into RNA (particularly mRNA).
Transcription is a mechanism in which the RNA polymerase enzyme converts information from DNA to mRNA.
There are three steps of transcription in prokaryotes: initiation, elongation and termination.

Initiation: In this step, the RNA polymerase enzyme attaches to the DNA sequence at the promoter along with the initiation factor (sigma) and begins transcription.
Elongation: In this phase, the nucleoside triphosphate RNA polymerase enzyme acts as a substrate and polymerizes the template nucleotides mostly as complementary strands.
Termination: The initiation factor at its termination point of the DNA sequence is replaced by the terminator factor (rho) in this process. RNA and RNA polymerase enzyme detachment with rho factor occurs at this level.

There are 3 regions in the transcription unit: the promoter, the structural gene, and also the terminator. There are two strands of the structural gene, identified as the template strand as well as the coding strand.

Note: A protein-encoding DNA transcription unit can contain both a coding sequence to be encoded into a protein and regulatory sequences that guide and control the production of that protein.