After transcription, a eukaryotic pre-mRNA molecule undergoes several modifications before it can be translated into protein. One crucial step in this process involves the removal of non-coding regions. What is the primary purpose of removing introns from a pre-mRNA molecule during splicing?
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The answer
Correct answer: D. To ensure that only the protein-coding exon sequences are translated into a functional polypeptide chain.
Tested concept: RNA processing and splicing
Explanation
Splicing is the process by which non-coding intron sequences are removed from a pre-mRNA molecule, and the remaining protein-coding exon sequences are ligated together. This ensures that the mature mRNA contains a continuous coding sequence that can be accurately translated into a functional polypeptide chain without interruption by non-coding regions. Distractor A is incorrect because protection from degradation is primarily a function of the 5' cap and the poly-A tail, not the removal of introns. Distractor B is incorrect because while mRNA maturation is necessary for export, the primary purpose of intron removal itself is not to directly facilitate transport, but rather to create a functional coding sequence. Distractor C is incorrect because ribosome binding and initiation of protein synthesis are primarily mediated by the 5' cap and specific sequences within the mRNA, not directly by the removal of introns.
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