Which enzyme connects RNA nucleotides to a DNA template during transcription?

During the process of transcription, RNA polymerase plays a crucial role in synthesizing RNA from a DNA template. This enzyme binds to a specific region of the DNA, known as the promoter, and unwinds the DNA strands, providing access to the DNA sequence that will serve as the template for RNA synthesis.

Once attached to the promoter, RNA polymerase facilitates the formation of RNA by connecting complementary RNA nucleotides to the growing RNA strand, following the base-pairing rules where adenine pairs with uracil (in RNA) and cytosine pairs with guanine. This reaction involves the addition of nucleotides one at a time, and as RNA polymerase moves along the DNA, it catalyzes the polymerization of RNA, ultimately producing a single-stranded RNA transcript that is complementary to the DNA template.

The other enzymes listed, such as DNA polymerase, which is involved in DNA replication, and ligase, which joins DNA fragments together, do not function in the context of transcription. Ribonuclease, which is involved in the degradation of RNA, also does not participate in the synthesis of RNA from a DNA template. Therefore, RNA polymerase is the enzyme specifically responsible for this essential step in gene expression.