Question

__________ functions in expression of 18 and 28S ribosomal genes and is largely localized to the nucleolar region of the nucleous.

-Reverse transcriptase
- RNA-dependent RNA polymerase
- RNA polymerase III
-RNA polymerase II
-RNA polymerase I

Answer 1

RNA polymerase I is the enzyme localized to the nucleolar region responsible for the expression of 18 and 28S ribosomal genes, differentiating it from RNA polymerases II and III which transcribe protein-coding genes and other structural RNAs respectively.

Step-by-step explanation:

The function that is largely localized to the nucleolar region of the nucleus and that is responsible for the expression of 18 and 28S ribosomal genes is that of RNA polymerase I. This polymerase specifically synthesizes all of the rRNAs from the tandemly duplicated set of 18S, 5.8S, and 28S ribosomal genes, which are structural components of the ribosome, instrumental to the process of translation. Not to be confused with RNA polymerase II, which synthesizes all protein-coding nuclear pre-mRNAs, or RNA polymerase III, which transcribes a variety of structural RNAs including the 5S pre-rRNA, pre-tRNAs, and small nuclear pre-RNAs.