This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Structure and function of protein, Subject name: Biochemistry
Which does not play a role in protein synthesis? 
Select and explain. 
A. Exon, B. Intron, C. m-RNA, D. ATP
B: Intron
Answer: B: Intron 
Explanation: The gene contains exons and introns. The introns need to be separated out and exons must be joined as they are actual amino acid coding sequences. Specific nucleases and ligases bring about this function. These changed an RNA into functional m-RNA.Ref: Textbook of medical biochemistry, MN Chatterji, 8th edition, page no: 262