What role do non-coding DNA sequences such as introns play in mRNA processing?

Non-coding DNA sequences, particularly introns, play a crucial role in mRNA processing by being removed from the primary transcript during the maturation of mRNA. This process, known as splicing, ensures that only the coding sequences, or exons, are retained in the final mRNA that is translated into a protein. By excising introns, the cell can produce a functional mRNA molecule that accurately reflects the coding information necessary for protein synthesis.

The significance of this removal is underscored by the fact that the presence of introns and their subsequent splicing can also facilitate alternative splicing. This process allows a single gene to encode multiple proteins, thereby increasing the diversity of proteins that a cell can produce.

In contrast, the other options do not accurately describe the role of introns. The retention of introns in the final mRNA sequence is not the case, as they are specifically excised to ensure the mRNA is a perfect template for translation. While introns may play a role prior to the mature mRNA phase, they do not contribute directly to the transcription process of mRNA itself, as that refers to the synthesis of the complete pre-mRNA including both exons and introns. Finally, introns do not initiate