Processing

Question 1

What enzymes create the 5’ end cap and what site are they recruited to?

Answer 1

Capping enzymes create the 5’ cap and attach at the CTD of RNA Polymerase after phosphorylation of Ser5.

Question 2

What is the 5’ end of the mRNA capped by?
and what is the significance of this?

Answer 2

7-methylguanosine triphosphate caps mRNA. It is the distinguishing factor from others, it helps binding to the ribosome and stability as well as protection from ribonucleases

Question 3

What are intron recognised by for splicing, where are they located and where do they move to?

Answer 3

Splicing proteins recognise introns. They are bound to the CTD of RNA Pol and are transferred to the intron/exon junctions as the mRNA emerges.

Question 4

Where and on what molecules does splicing occur and what is the purpose of this molecule?

Answer 4

It occurs in the nucleus on splicosomes. The splicesosome adds more splicing factors.

Question 5

What is mRNA splicing performed by in the splicesosome?

Answer 5

It is performed by small nuclear ribonuclearprotein (snRNP) which is a molecule composed on snRNA and proteins that recognises the splicing signals on the RNA polymer.

Question 6

What is the workflow of splicing of introns?

Answer 6

1. specific adenine nucleotide in intron attacks 5’ splice site
2. The adenine cuts the backbone of RNA.
3. The intronic 5’ end covalently binds A to form a loop.
4. The 3’ end of the exon reacts with the next exon and are joined together to release the lariat-like intron.

Question 7

What is the end result of alternative splicing?

Answer 7

Different forms of a protein from the same gene called trancrip variants, splice variants or isoforms.