Define “transcription termination.”

Transcription termination is the process that occurs when RNA polymerase synthesizes RNA from a DNA template and subsequently halts the elongation of the RNA strand. This crucial step allows for the proper release of the newly formed RNA molecule from the transcription complex. During transcription termination, specific sequences in the DNA signal the RNA polymerase to stop adding nucleotides to the growing RNA strand, leading to the dissociation of the RNA polymerase, the completed RNA transcript, and the DNA template. This event is vital as it ensures that the RNA molecule is fully synthesized and can undergo further processing, which is essential for its eventual translation into a protein.

The other choices do not accurately describe transcription termination. The completion of mRNA processing refers to events like capping, polyadenylation, and splicing that occur after transcription is completed. The binding of transcription factors relates to the initiation of transcription, where these proteins help recruit RNA polymerase to the promoter region of the gene. The initial step in RNA synthesis corresponds to the beginning of transcription, where DNA unwinds and RNA polymerase synthesizes the first nucleotides. Thus, the defining feature of transcription termination is indeed the stopping point and release of the RNA molecule by RNA polymerase.