This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Poly 'A' tail attached at 3' end of mRNA helps in? 
Select and explain. 
A. Unwinding of mRNA, B. Stabilization of mRNA, C. Polymerization of mRNA, D. Transcription of mRNA
B: Stabilization of mRNA
Answer: B: Stabilization of mRNA 
Explanation: Ans. is 'b' i.e., Stabilization of mRNA At the 51-end, mRNA possesses a 7-methylguanosine triphosphate cap which helps in the recognition of mRNA in protein biosynthesis and it helps to stabilize the mRNA by preventing attack of 51-exonuclease. At its 31-end, there is a poly-A tail made up of several adenylate residues which stabilize mRNA by preventing attack of 31-exonuclease.