Final answer:
An enhancer is a DNA sequence in eukaryotic cells that can increase the transcription of a gene located some distance away. Transcription factors bind to enhancers, and through DNA folding, these enhancers interact with promoters to enhance gene expression.
Step-by-step explanation:
A eukaryotic DNA sequence that affects transcription at distant promoters is called a enhancer. Enhancers are critical regulatory elements in eukaryotic DNA that can increase the transcription of genes, even if they are located thousands of nucleotides away from the gene they regulate. These enhancers are made up of short DNA sequences known as distal control elements.
When transcription factors bind to an enhancer region, it can greatly increase the transcription of a distant gene by facilitating the interaction between activators and the transcription initiation complex. This interaction is made possible by the three-dimensional folding of the DNA which brings the enhancer into proximity with the gene's promoter.