Transcription

TRANSCRIPTION
Introduction:-
Transcription is a process of formation of transcript i.e. RNA.

It takes place by usual process of complement base pairing catalysed by enzyme RNA
Polymerase.

The strand of DNA which serves as template for the synthesis of RNA is known as
template strand and is complementary to the RNA chain.

The other strand is called coding strand as it's sequence of bases is identical to newly
formed mRNA.

Transcription starts from first base pair called start point.

From this point RNA Polymerase moves along the template synthesizing RNA until it
reaches the Terminator sequence.

The process of RNA synthesis takes place in 5'-3' direction.

Process of Transcription :-
Transcription reaction can be divided into 3 stages:

1. Initiation

2. Elongation

3. Termination

1. Initiation:- Initiation of transcription describes the formation of first phosphodiester
between two nucleotides in an RNA

RNA Polymerase as holo enzyme binds at the promoter and start the initiation reaction
by forming a closed binary complex.

Sigma factor confers the ability to recognise the consensus sequence within the
promoter.

2. Elongation:- Elongation involves the movement of transcription bubble by
disrupting DNA structure.