The conversation between human and AI assistant.
[|Human|] Given the following paragraph on gene regulation, what are operons and where do they occur?
[|AI|] Operons are clusters of genes that share the same promoter. They occur mainly in prokaryotes and some lower eukaryotes such as Caenorhabditis elegans.
[|Human|] 
Given the following paragraph on gene regulation, what are operons and where do they occur?