Question

Which one of the following is transcribed by RNA polymerase III in eukaryotes?

• A. 18S rRNA
• B. 28S rRNA
• C. miRNA
• D. tRNA

Answer 1

The Correct Option is D

In eukaryotic cells, RNA polymerase III is one of the three main types of RNA polymerases responsible for transcribing various types of RNA. Each type of RNA polymerase transcribes a specific set of genes. Let's briefly explore the functions of the three RNA polymerases in eukaryotes:

• RNA Polymerase I: Primarily transcribes ribosomal RNA (rRNA) genes, specifically the 18S, 5.8S, and 28S rRNA, which are components of the ribosome.
• RNA Polymerase II: Responsible for transcribing messenger RNA (mRNA) genes, which are later translated into proteins. It also transcribes some small nuclear RNAs (snRNAs) and microRNAs (miRNAs).
• RNA Polymerase III: Transcribes transfer RNA (tRNA) genes, as well as the 5S rRNA and some other small RNAs.

Based on the functions described above, RNA Polymerase III is responsible for transcribing the following key RNAs:

1. tRNA - Transfer RNA, which is essential for translation and delivering amino acids to the ribosome.
2. 5S rRNA - A component of the large subunit of the ribosome.
3. Other small RNAs like some nuclear RNAs associated with the splicing machinery.

Let's analyze the options:

• 18S rRNA - Transcribed by RNA Polymerase I.
• 28S rRNA - Transcribed by RNA Polymerase I.
• miRNA - Usually transcribed by RNA Polymerase II.
• tRNA - Transcribed by RNA Polymerase III.

As we can see, the correct answer to what RNA Polymerase III transcribes in eukaryotes is tRNA.