Eukaryotes coordinate gene expression, which is not possible via operons due to the dispersed nature of eukaryotic genes, by using transcription factors to activate the genes which are needed at the same time. This is especially true for specific transcription factors.
Work Step by Step
Transcription factors act like supervisors in a work place. Just as the supervisor might not actually assemble parts of a car but, rather, direct workers to cooperate to effectively assemble a car, transcription factors are not enzymes making a product. Instead, they tell the cell which genes to express for effective and efficient cellular work.