In prokaryoic operons coordinate synthesis of proteins with related funcions. In eukaryotes, the coordinated synthesis of proteins with related funcions also occurs, but without the need to organize genes under the control of a single promoter in an operon. Two general categories of eukaryoic gene regulaion: short-term and long-term regulaion. Short-term regulaion: gene sets are quickly turned on or of in response to changes in environmental/physiological condiions in the cell"s or organism"s environment: most similar to prokaryoic gene regulaion. Long-term regulaion involves regulatory events required for an organism to develop and difereniate: occurs in mulicellular eukaryotes, not in simpler, unicellular eukaryotes. 14. 2a in eukaryotes, regulaion of gene expression occurs at several levels. Gene expression in eukaryotes is regulated at more levels; the most important is transcripional regulaion. Transcripional regulaion: determines which genes are transcribed: regulaion of transcripion iniiaion, chromain remodelling to make genes accessible for transcripion.