Question

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

Answer 1

Transcription is a process in which the information from DNA is transferred to mRNA by the enzyme RNA polymerase.

Transcription in prokaryotes is carried out in three stages: Initiation, elongation and termination.

Initiation: In this step RNA polymerase enzyme along with initiation factor (sigma) binds with DNA sequence at promotor and starts transcription.

Elongation: In this step RNA polymerase enzyme nucleoside triphosphate act as a substrates and polymerises the nucleotides of templates as a complementary strand.

Termination: In this step terminator factor (rho) replaces the initiation factor at the termination point of DNA sequence.At this stage detachment of RNA and RNA polymerase enzyme with rho factor takes place.

The transcription unit is composed of three regions, promoter, structural gene and the terminator. In the structural gene, there are two strand known as the template strand and the coding strand.