ABSTRACT
Eukaryotic RNA synthesis is carried out by three separate RNA polymerases, while RNA synthesis in prokaryotic cells is performed by a single RNA polymerase. The precursor to three of the four eukaryotic rRNAs (the 28S, 5.8S, and 18S rRNAs) is produced by RNA polymerase I in the nucleolus of the cell. The precursors of the mRNAs are made by RNA polymerase II and the small RNAs (tRNAs and the 5S rRNAs) or their precursors are made by RNA polymerase III.
