What is the role of RNA polymerase in transcription?

• A. Join nucleotides to form RNA strands
• B. Unzip the DNA double helix
• C. Methylate DNA
• D. Synthesize proteins

Answer: (A)

RNA polymerase is the enzyme that carries out transcription by building RNA using the DNA template. It catalyzes the formation of phosphodiester bonds between incoming ribonucleotides, extending a growing RNA strand in the 5' to 3' direction. It reads the template DNA to determine the RNA sequence and uses ribonucleoside triphosphates (A, C, G, U) as the building blocks, without needing a primer. While the enzyme locally unwinds DNA to access the template, its primary role during transcription is to join nucleotides to form the RNA transcript, not to synthesize proteins or methylate DNA. That’s why joining nucleotides to form RNA strands is the best description of its role.