Question

Describe the ways messenger RNA is post transcriptionally processed. What are the significance of these events?

Answer 1

Answer=

the ways messenger RNA is post transcriptionally processed are as follows:

1] 5' Cap -Both ends of a pre-mRNA are modified by the addition of chemical groups.The group at the beginning i.e.5' end is called as cap.

The 5'cap is added to the first nucleotide in the transcript during transcription.The cap is a modified guanine G nucleotide,

significance- It protects the transcript from being broken down.

also helps the ribosome attach to the mRNA and start reading it to make a protein.

2]Poly A tail= The polyadenylation is the addition of a poly A tail to a mRNA.

The poly A tail consists of multiple adenosine monophosphates ,it is a stretch of RNA that has only adenine bases.

This process begins as the transcription of a gene terminates.

significance- The poly A tail is important for nuclear export,translation and stability of mRNA.

It protects the mRNA molecule from enzymatic degradation in the cytoplasm and aids in transcriptional termination,export of mRNA from the nucleus and translation.

3]RNA splicing- In this splicing ,specific parts of the pre-mRNA ,called introns are recognized and removedby a protein-and -RNA complex called the spliciosomes.Introns can be viewed as junk sequences .

The xons are pieces of RNA that are pasted together by the spliceosome to make final ,mature mRNA .

4]Alternative splicing - More than one mRNA can be made from the same gene.

Through alternative splicing ,we can encode more different proteins than we have genes in our DNA.