What function does RNA polymerase have, and where does it operate?

What function does RNA polymerase have, and where does it operate?

• A. Unwinding DNA and adding RNA nucleotides to the DNA template
• B. Synthesizes DNA from an RNA template
• C. Splices RNA after transcription
• D. Translates mRNA into protein

Answer: (A)

Transcription by RNA polymerase is about reading a DNA template to make RNA. It starts by unwinding a short segment of DNA to expose the template strand, then it adds ribonucleotides to the growing RNA chain that are complementary to that template. The RNA is built in the 5' to 3' direction, producing an RNA transcript that reflects the gene’s sequence (uracil replaces thymine). Where this happens depends on the cell type. In eukaryotic cells, transcription occurs in the nucleus, because the genome is housed there. In prokaryotic cells, there is no nucleus, so transcription happens in the cytoplasm. This function aligns with the idea of RNA polymerase unwinding DNA and synthesizing RNA from the DNA template. Other options describe processes carried out by different machineries (splicing by spliceosomes, translation by ribosomes, or reverse transcription), which are not the primary transcription function.

Transcription by RNA polymerase is about reading a DNA template to make RNA. It starts by unwinding a short segment of DNA to expose the template strand, then it adds ribonucleotides to the growing RNA chain that are complementary to that template. The RNA is built in the 5' to 3' direction, producing an RNA transcript that reflects the gene’s sequence (uracil replaces thymine).

Where this happens depends on the cell type. In eukaryotic cells, transcription occurs in the nucleus, because the genome is housed there. In prokaryotic cells, there is no nucleus, so transcription happens in the cytoplasm.

This function aligns with the idea of RNA polymerase unwinding DNA and synthesizing RNA from the DNA template. Other options describe processes carried out by different machineries (splicing by spliceosomes, translation by ribosomes, or reverse transcription), which are not the primary transcription function.