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In bacteria, genes for a given pathway are often linked together as "cassettes." The cassettes were like all-in-one kits with all the genes in the right order to make precursors and final product (in our case we spliced in about 7 genes for bacterial bioluminescence). http://davidcwhite.org/fulltext/382.pdf
I'm sure it's much more complicated in eukaryotes.

Yeah, Eukaryotic gene expression is a lot more complicated. You've got introns, histones, and a bunch of other regulatory factors to consider.