Final answer:
RNA polymerase is responsible for synthesizing RNA from a DNA template during the process of transcription by adding nucleotides to the growing RNA strand.
Step-by-step explanation:
The role of RNA polymerase is synthesizing RNA from a DNA template. Specifically, during transcription, RNA polymerase binds to the promoter region of DNA, unwinds the DNA segment, and uses one of the strands as a template. It aligns nucleotides with their complementary bases on the DNA template strand and synthesizes RNA by adding these nucleotides to the 3' end of the growing RNA strand. RNA polymerase does not require a primer to start synthesis, and unlike DNA polymerase, it incorporates uracil (U) rather than thymine (T) into the RNA strand.