During RNA processing, what happens to introns?

• A. They become exons
• B. They are translated into amino acids
• C. They are removed
• D. They remain untranslated

Answer: (C)

During RNA processing, introns are noncoding segments in the initial transcript that must be removed before the message can be used for protein production. The spliceosome recognizes the boundaries of each intron, cuts it out, and stitches the surrounding exons together, leaving a mature mRNA composed only of exons. This step is essential because introns do not encode amino acids and would disrupt the coding sequence if kept. After splicing, the mature mRNA is ready for translation, while introns may have regulatory roles or give rise to other RNAs but are not part of the translated message.