Question

Can you explain three ways that transcriptional repression can occur , please use some examples, thanks

Answer 1

formation of mRNA from DNA is called as transcription.it is heterocatalytic function of DNA. template of DNA called sense strand is involved. the segment of DNA involved in transcription is citron , which have a promoter region where initiation is started and terminator region where transcription ends. enzyme involved in transcription is RNA polymerise - II which consist 5 polypeptide and sigma factor.

sigma factor recognise promoter site while remaining core enzyme take part in chain elongation. after transcription, DNA molecule reassociate to form it's original structure.

In eukaryotic hn RNA ( heterogeneous nuclear RNA) which consist exon ( it is coded region) and intron ( it is non coded region) formed in nucleus and diffuse in cytoplasm is also known as split gene which goes to transcription changes for removing the intros and later formed mRNA.

transcription consist of three phenomenon :-

1. Initiation = initiation start with the help of sigma factor of RNA polymers enzyme. at the cap region, which have 7 methyl guanosine residue at the 5'.

2. elongation = elongation is done by core enzyme which move along the sense strand.

3. termination = In prokaryotes termination is done by rho factor. in eukaryotes poly A tail is responsible for termination at the 3'.