Question

The splicing of introns out of an mRNA molecule is catalyzed by

A. RNA molecules that base pair with the splice sites to promote intron removal.

B. proteins that contain metal ions to pull electrons from the phosphate bonds.

C. RNA molecules that act as a template for new RNA synthesis using exons only.

D. proteins that act as nucleases to chew away and remove the introns.

Answer 1

The splicing of introns from an mRNA molecule is performed by spliceosomes, which are complexes made of proteins and snRNAs.

Step-by-step explanation:

The splicing of introns out of an mRNA molecule is catalyzed by protein complexes called spliceosomes. These spliceosomes are composed of both proteins and RNA molecules known as small nuclear RNAs (snRNAs). They function by recognizing sequences at the 5' and 3' end of an intron, ensuring precise removal of all introns from the pre-mRNA. It's crucial that introns are removed accurately; otherwise, if the splicing process errs by even one nucleotide, the exons could be rejoined incorrectly, which would alter the reading frame and likely result in a dysfunctional protein. Spliceosomes facilitate the critical splicing process by bringing together the necessary components for intron removal and exon rejoining within the nucleus of eukaryotic cells.