Final answer:
DNA opens at the promoter region during prokaryotic transcription initiation. This region is where RNA polymerase and other transcription factors bind to start the transcription process.
Step-by-step explanation:
In prokaryotic transcription, DNA opens during initiation at the promoter region. This is a DNA sequence where the transcription machinery, including RNA polymerase and sigma factor, bind to initiate transcription. The promoter contains specific consensus sequences at the -10 and -35 regions relative to the initiation site; these sequences are TATAAT (the TATA box) and TTGACA, respectively. The -10 region, being A-T-rich, facilitates the unwinding of the DNA template, allowing transcription to begin. This process is different from DNA replication, which involves a replication fork, and also distinct from processes occurring at exon-intron junctions or termination sequences.