What is the primary difference between an intron and an exon in eukaryotic RNA processing?

• A. Introns code for proteins, while exons do not.
• B. Exons are non-coding regions, while introns are coding regions.
• C. Exons are removed during RNA splicing, while introns remain in the mature mRNA.
• D. Introns are removed during RNA splicing, while exons remain in the mature mRNA.

Answer: (D)

Verified step by step guidance

1. Understand the basic structure of eukaryotic genes: Eukaryotic genes consist of coding regions called exons and non-coding regions called introns.
2. Learn about RNA processing: During transcription, the entire gene, including both introns and exons, is transcribed into a precursor mRNA (pre-mRNA).
3. Explore the process of RNA splicing: RNA splicing is a crucial step in RNA processing where introns are removed from the pre-mRNA.
4. Recognize the role of exons: After splicing, the remaining exons are joined together to form the mature mRNA, which is then translated into a protein.
5. Clarify the primary difference: Introns are non-coding regions that are removed during RNA splicing, while exons are coding regions that remain in the mature mRNA.