Question

What is the role of RNA polymerase III in the process of transcription in eukaryotes

• A. Transcribes only snRNAs
• B. Transcribes rRNAs (28S, 18S and 5.8S)
• C. Transcribes tRNA, 5s rRNA and snRNA
• D. Transcribes precursor of mRNA

Answer 1

The Correct Option is C

RNA polymerase III is one of the three main types of RNA polymerases found in eukaryotic cells, each having distinct roles during the process of transcription. The key function of RNA polymerase III is to transcribe the genes that code for small RNA molecules. Among these are:

• tRNA (transfer RNA): Essential for the translation process as it carries amino acids to the ribosome, helping to decode the mRNA into a polypeptide.
• 5S rRNA (5S ribosomal RNA): A component of the large subunit of the ribosome, playing a crucial role in protein synthesis.
• snRNA (small nuclear RNA): Part of the spliceosome machinery, which is involved in splicing pre-mRNA and removing introns.

The correct option for RNA polymerase III's role in eukaryotic transcription is:

• Transcribes tRNA, 5s rRNA, and snRNA

Let's evaluate why the other options are incorrect:

• Transcribes only snRNAs: RNA polymerase III transcribes snRNA, but it also transcribes tRNA and 5S rRNA.
• Transcribes rRNAs (28S, 18S, and 5.8S): These are transcribed by RNA polymerase I, not RNA polymerase III.
• Transcribes precursor of mRNA: The precursor of mRNA, or pre-mRNA, is transcribed by RNA polymerase II.

Therefore, based on the role and specificity of RNA polymerase III, the correct answer is that it transcribes tRNA, 5S rRNA, and small nuclear RNA (snRNA).