RNA polymerase binds to the promoter and initiates transcription (initiation). It uses nucleosides triphosphates as substrate and polymerises in a template dependent fashion following the rule of complimentarity.
It facilitates opening of the helix and continues elongation. Only short stretch of RNA remains bound to the enzyme.
Once the polymerases reaches the terminator region, nascent RNA falls off, so also the RNA polymerase . This results in termination of transcription.
RNA polymerase is only capable of catalysing the process of elongation . It associates transiently with initiation factor ( ∂) to initiate and terminate transcription.