Eukaryotic cells contain three nuclear RNA polymerases that transcribe different classes of genes. Which RNA polymerase transcribes precursor ribosomal RNA (45S rRNA)?
- A RNA polymerase III
- B RNA polymerase II
- C RNA polymerase I ✓
- D RNA polymerase IV
Correct answer: C. RNA polymerase I
Explanation
RNA polymerase I transcribes the 45S precursor rRNA in the nucleolus, which is processed into 18S, 5.8S, and 28S rRNAs. RNA polymerase II transcribes mRNA precursors and most small nuclear RNAs. RNA polymerase III transcribes tRNAs, 5S rRNA, and other small RNAs. RNA polymerase IV is found only in plants and is involved in siRNA synthesis.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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