Final answer:
Transcriptionally active genes are located in euchromatin, which is the less condensed region of a chromosome territory. This region allows transcriptional machinery access to the genes. Enhancers also facilitate increased transcription by interacting with promoters, even at a distance.
Step-by-step explanation:
Regions of transcriptionally active genes, also known as euchromatin, are found within the less dense areas of a chromosome territory during the interphase of the cell cycle. These areas are where the DNA is not as tightly packed around nucleosomes, allowing for transcriptional machinery to access specific genes for transcription. Enhancers, which can be located upstream, within, or downstream of the gene, also play a crucial role in increasing transcription by binding transcription factors, even if they are thousands of nucleotides away, due to the DNA folding and bringing them into proximity with the promoter region.