Final answer:
The template for RNA polymerase is DNA, and the new RNA chain is antiparallel and complementary to the template. Transcription involves RNA polymerase synthesizing RNA from the DNA antisense strand by forming nucleotides complementary to the template in the 5'→3' direction.
Step-by-step explanation:
The template for RNA polymerase is DNA, and the new RNA chain is antiparallel and complementary to the template. During the process of transcription, RNA polymerase synthesizes RNA using the antisense strand of the DNA as a template. This enzyme adds complementary RNA nucleotides to the growing RNA strand in the 5'→3' direction of the RNA molecule itself, which corresponds to the 3'→5' direction on the DNA template strand. This synthesis occurs without needing a primer and is initiated at a specific DNA sequence called a promoter. As the RNA polymerase moves along the DNA template, the double-stranded DNA unwinds in front of the transcription machinery to expose the template strand. Then, each new RNA nucleotide is selected by Watson-Crick base pairing interactions, with uracil (U) incorporated into the RNA strand in place of thymine (T), which pairs with adenine (A) in the DNA template strand. In conclusion, the mechanism of transcription involves the creation of an RNA molecule that is complementary to the DNA template strand, building the RNA strand in the antiparallel direction to the DNA template strand.