CENTRAL DOGMA :: PART 7

POST TRANCRIPTIONAL MODIFICATIONS

Genes in eukaryotes contain introns (non–coding regions) which are not necessary for protein synthesis. The removal of these introns and joining of all exons (coding region of a gene) is called post transcriptional modification. It takes place only in Eukaryotes, as prokaryotes don’t have introns in their genes.  

Splicing is important because

(1)    It’s a process of maturation.

(2)    The new mRNA is likely to get attacked by enzymes which degrade RNA.

(3)     The non-coding part is removed, only the coding part in retained.

What Happens in Splicing?

(

1)   Capping and tailing i.e., 7-methylguanosine is added to one end and a long chain of Adenosine is added to another end.

(2)    The unwanted (which are not useful in protein production) parts in mRNA are removed and the rest are joined to form a fully mature mRNA. It is than send to cytoplasm for translation.

(3)    The mRNA from which gives rise to a mature mRNA is called a pre-mRNA.