Splicing of pre-mRNA is carried out by which complex?

Splicing of pre-mRNA is carried out by which complex?

• A. Spliceosome
• B. Ribosome
• C. Ligase
• D. Polymerase

Answer: (A)

Splicing of pre-mRNA is carried out by a large ribonucleoprotein machine called the spliceosome. This complex, composed of small nuclear RNAs (snRNAs) and numerous proteins, recognizes the splice sites at intron–exon boundaries and coordinates two transesterification reactions that remove the intron and join the exons to form mature mRNA. The spliceosome’s snRNAs help base-pair with the pre-mRNA to define where splicing occurs, and the catalytic activity is carried out within this RNA–protein assembly. In contrast, the ribosome is the molecular machine that translates mRNA into protein, polymerase enzymes synthesize nucleic acids, and ligases typically seal DNA ends or RNA fragments but do not drive the specific intron excision and exon ligation of pre-mRNA splicing.

Splicing of pre-mRNA is carried out by a large ribonucleoprotein machine called the spliceosome. This complex, composed of small nuclear RNAs (snRNAs) and numerous proteins, recognizes the splice sites at intron–exon boundaries and coordinates two transesterification reactions that remove the intron and join the exons to form mature mRNA. The spliceosome’s snRNAs help base-pair with the pre-mRNA to define where splicing occurs, and the catalytic activity is carried out within this RNA–protein assembly. In contrast, the ribosome is the molecular machine that translates mRNA into protein, polymerase enzymes synthesize nucleic acids, and ligases typically seal DNA ends or RNA fragments but do not drive the specific intron excision and exon ligation of pre-mRNA splicing.