Which enzyme synthesizes ribosomal RNA (rRNA) precursors inside the eukaryotic nucleolus? (Hard)
Answer and explanation
Correct answer: C. RNA Polymerase I
- Step 1: Eukaryotes possess three specialized nuclear RNA polymerases. Step 2. RNA Polymerase I transcribes large rRNA precursors (28S, 18S, 5.8S) in the nucleolus; Pol II transcribes mRNA and snRNA; Pol III transcribes tRNA and 5S rRNA. Answer: RNA Polymerase I. Why not the others: RNA Polymerase II transcribes protein-coding mRNA; RNA Polymerase III transcribes tRNA and 5S rRNA; DNA Polymerase alpha initiates replication.
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