Which of the following statements about RNA splicing is FALSE?

• A. Introns are removed from pre-mRNA
• B. Exons are joined together after intron removal
• C. Splicing occurs in the nucleus
• D. Small nuclear ribonucleoproteins do not participate in splicing

Answer: (D)

RNA splicing relies on the spliceosome, a complex built around small nuclear ribonucleoproteins that recognize splice sites on the pre-mRNA and drive the two key chemical steps that remove introns and ligate exons. This processing happens in the nucleus, turning the transcript into mature mRNA that can be exported for translation. The statement that snRNPs do not participate is false because these particles are essential components of the spliceosome and are directly involved in recognizing exon–intron boundaries and catalyzing the reactions that remove introns. Introns are removed and exons are joined after intron removal, and splicing occurs in the nucleus, so those statements describe correct aspects of the process.