Compare a promoter and an enhancer in terms of location and function.

• A. Promoter is proximal to the gene and is the site of RNA polymerase binding; enhancer can be far away, upstream or downstream, and increases transcription via activators.
• B. Promoter is typically distal and regulates efficiency; enhancer is proximal and binds RNA polymerase directly.
• C. Promoter and enhancer both always sit adjacent to the gene and recruit identical transcription factors.
• D. Promoter functions after transcription; enhancer controls chromatin structure only.

Answer: (A)

The question tests how promoters and enhancers differ in location and function. A promoter sits right at the gene’s start region and is where RNA polymerase II and the general transcription machinery assemble to begin transcription. It’s typically proximal to the gene, defining the transcription start site.

An enhancer, in contrast, can be far from the gene—upstream, downstream, or even inside an intron. It doesn’t recruit RNA polymerase directly. Instead, it binds specific transcription factors (activators) that boost transcription by helping bring the promoter and the transcriptional machinery together through DNA looping and coactivator complexes. This arrangement makes transcription more robust and can work even when the enhancer’s orientation or distance varies.

The other options mix up these roles: one reverses which element is proximal and which binds RNA polymerase; another claims both lie next to each other and recruit the same factors; and another says promoters act after transcription and enhancers only alter chromatin structure. Each of those statements misstates either the location or the function of promoters and enhancers.