Transcription
- Transcription is the process where genetic information from a strand of DNA is copied to form the RNA. The RNA is formed as a complementary strand to the DNA strand. Here during the addition of bases in RNA, adenine forms a base pair with uracil instead of thymine.
- During transcription, one of the strands of DNA acts as a template for mRNA formation. RNA polymerase enzyme synthesises the mRNA. Transcription is carried out for a particular DNA segment which is required further for gene expression.
- A transcription unit in DNA comprises three regions, namely, a promoter, structural gene and a terminator. DNA dependent RNA polymerase brings about the addition of nucleotides in 5′-3′ direction.
- Promoter is the region where RNA polymerase binds. Terminator defines the end of transcription.
- RNA polymerase binds to the promoter and initiates the process of transcription This is the initiation stage.
- It adds nucleotides following the rule of complementarity. It also facilitates opening of the helix which then ensures the elongation of the strand.
- Once the polymerase reaches the terminator region, the newly made mRNA falls off. The RNA polymerase also detaches. This results in termination of transcription.