This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Transcription, Subject name: Biochemistry
[{'content': 'Which of the following cis-acting elements typically resides adjacent to or overlaps with many prokaryotic promoters? \nSelect and explain. \nA. Regulatory gene, B. Structural gene(s), C. Repressor, D. Operator', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Operator resides adjacent to or overlaps with many prokaryotic promoters. Operator site should be free for the movement of RNA polymerase. Operator region is unique for prokaryotic operons. Eukaryotes do not contain operator elements in the genome. Operator locus exhibit two-fold symmetry and an inveed palindrome.', 'role': 'assistant'}]