What is the mechanism by which RNA polymerase synthesizes RNA?

The mechanism by which RNA polymerase synthesizes RNA involves using a DNA template strand to create complementary RNA. This process, known as transcription, occurs in several key steps. RNA polymerase binds to a specific region on the DNA called the promoter, which indicates where transcription should begin. Once bound, RNA polymerase unwinds the DNA double helix and starts synthesizing a strand of RNA by incorporating ribonucleotides complementary to the DNA template strand. For example, if the DNA template has an adenine (A), RNA polymerase will incorporate a uracil (U) into the growing RNA strand, as RNA contains uracil instead of thymine (T). This synthesis occurs in the 5' to 3' direction, allowing the RNA molecule to grow as more nucleotides are added.

By following this mechanism, RNA polymerase ensures that the RNA strand produced is complementary to the DNA template, which is critical for accurate gene expression and the production of proteins during translation. Other options such as translating DNA sequences into proteins, incorporating amino acids, or binding to ribosomes pertain to processes that occur after transcription and do not accurately describe the role of RNA polymerase in RNA synthesis.