Which ribonucleoprotein complex excises introns from eukaryotic precursor messenger RNA?
Answer and explanation
Correct answer: A. Spliceosome composed of small nuclear RNAs and associated proteins
The spliceosome (consisting of snRNAs U1, U2, U4, U5, and U6 plus proteins) catalyzes pre-mRNA splicing by recognizing conserved 5' splice, branch point, and 3' splice sites. Ribosomes translate mRNA; proteasomes degrade ubiquitinated proteins.
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