Transcription

TRANSCRIPTION
‘’Transcription is the process where information present on a specific part of DNA is copied in a
complementary form of mRNA.’’


MECHANISM OF TRANSCRIPTION:
The process of transcription can be divided into three stages
1. Initiation
2. Elongation
3. Termination


1. INITIATION:
“The process starts when an enzyme called RNA polymerase binds to a specific region of
the DNA called the promoter.”

• Only one of the two strands of DNA is transcribed. This strand is called template strand
or the antisense-strand. The opposite strand is known as coding or sense strand.



RNA polymerase:
This is an enzyme which synthesizes the RNA against a template of DNA.
Features of RNA polymerase:
• The RNA polymerase enzyme synthesizes the RNA from 5'→ 3' direction.
• There is only one type of RNA polymerase in prokaryotes, which is responsible for the
synthesis of all the 3 types of RNAs viz, rRNA, mRNA and tRNA.
• In eukaryotes, there are three types of RNA polymerases namely
RNA polymerase I, which synthesizes rRNA.
RNA polymerase II, which synthesizes mRNA.
RNA polymerase III, which synthesizes tRNA.