Final answer:
During the melting stage of transcription initiation, the DNA double helix partially unwinds at the promoter region, allowing RNA polymerase to bind and form a transcription bubble.
Step-by-step explanation:
During the melting stage of transcription initiation, the DNA double helix partially unwinds in the region of mRNA synthesis, forming a transcription bubble. This unwinding allows the enzyme RNA polymerase to bind to the promoter region of the gene. The RNA polymerase then separates the DNA strands, creating a single-stranded DNA template for mRNA synthesis.
Example: Imagine the double-stranded DNA is like a zipper. During the melting stage, the zipper is partially opened, creating a small opening. This opening allows the RNA polymerase to thread through and bind to the promoter region, ready to transcribe the gene.