Which RNA processing complex removes introns from pre-mRNA?

Which RNA processing complex removes introns from pre-mRNA?

• A. Ribosome
• B. DNA polymerase
• C. Ligase
• D. Spliceosome

Answer: (D)

Introns are removed from pre-mRNA by the spliceosome, a large RNA–protein complex that operates in the nucleus to carry out RNA processing. It recognizes splice sites and the branch point, brings the exons together, and catalyzes two transesterification reactions that excise the intron as a lariat and join the adjacent exons to form mature mRNA. The spliceosome relies on small nuclear RNAs (snRNAs) and associated proteins (snRNPs) to guide this precise cutting and joining, which is essential for producing functional mRNA and enabling possible alternative splicing. The other enzymes listed don’t handle RNA splicing. The ribosome translates mRNA into protein, DNA polymerase copies DNA, and ligase seals breaks in DNA or joins Okazaki fragments.

Introns are removed from pre-mRNA by the spliceosome, a large RNA–protein complex that operates in the nucleus to carry out RNA processing. It recognizes splice sites and the branch point, brings the exons together, and catalyzes two transesterification reactions that excise the intron as a lariat and join the adjacent exons to form mature mRNA. The spliceosome relies on small nuclear RNAs (snRNAs) and associated proteins (snRNPs) to guide this precise cutting and joining, which is essential for producing functional mRNA and enabling possible alternative splicing.

The other enzymes listed don’t handle RNA splicing. The ribosome translates mRNA into protein, DNA polymerase copies DNA, and ligase seals breaks in DNA or joins Okazaki fragments.