RNA processing includes which steps?

• A. RNA processing includes the excision of introns, splicing of exons, and addition of a 5' cap and poly(A) tail.
• B. Translation of proteins
• C. DNA replication
• D. Protein folding

Answer: (C)

RNA processing refers to the post-transcriptional modifications that convert a primary RNA transcript into a mature mRNA ready for export and translation. In eukaryotes, this includes removing noncoding introns and joining the remaining coding exons (splicing), adding a 5' cap, and adding a poly(A) tail at the 3' end. The 5' cap and poly(A) tail help protect the transcript from degradation, assist export from the nucleus, and the cap aids ribosome recognition during translation. Splicing ensures that only the exons that encode the protein are joined together.

Translation, DNA replication, and protein folding are separate processes: translation is the ribosome-driven synthesis of protein after RNA is processed; DNA replication copies the genome; and protein folding occurs after translation to achieve the proper 3D structure. Therefore, the steps listed as intron removal, exon splicing, and 5' cap plus poly(A) tail addition correctly describe RNA processing.