Does RNA synthesis require a primer for initiation?

RNA synthesis does not require a primer for initiation. In contrast to DNA replication, where a primer is necessary to provide a starting point for DNA polymerases, RNA polymerases have the unique capability of initiating synthesis de novo. This means they can start RNA synthesis without the need for an existing strand to extend from. RNA polymerase binds to specific sequences of DNA known as promoters, where it can begin synthesizing RNA by adding ribonucleotides in a complementary manner to the DNA template. This characteristic is critical for the efficiency and regulation of gene expression, enabling timely responses to cellular signals and developmental cues.

In understanding this, it is clear why the other options suggesting various types of primers are incorrect. RNA synthesis is distinct from DNA synthesis in this fundamental aspect of initiation, reflecting the specialized roles and mechanisms of RNA polymerases.