Operon concept is applicable to eukaryotic species that have operons. These include nematodes, such as C. elegans, and the fruit fly, Drosophila melanogaster.
Yes, prokaryotes and some eukaryotes. These eukaryotes include nematodes and fruit flies.
So , the answer would be prokaryotes and some eukaryotes? I've seen somewhere in the net where they claim.. operon concept is only applicable to prokaryotes and not in eukaryotes. Thank you for answering me.