Which enzyme binds to the promoter region to initiate transcription?

• A. DNA polymerase
• B. RNA polymerase
• C. RNA ligase
• D. Helicase

Answer: (C)

Transcription starts when RNA polymerase binds to the promoter, a DNA sequence that marks where a gene begins. In bacteria, the RNA polymerase holoenzyme recognizes the promoter with help from a sigma factor, binds, and moves in to unwind the DNA so it can begin RNA synthesis. In eukaryotes, RNA polymerase II is recruited to promoter regions by general transcription factors, forming a preinitiation complex that opens the DNA and starts copying the template strand into RNA. This enzyme is what creates RNA from the DNA template, while other enzymes like DNA polymerase are involved in DNA replication, helicase mainly unwinds DNA rather than initiating transcription, and RNA ligase joins RNA fragments during processing rather than starting transcription.