The present invention relates to an isolated DNA sequence encoding an enzyme in the mevalonate pathway or the pathway from isopentenyl pyrophosphate to farnesyl pyrophosphate. Vectors and plasmids including such DNA are also set forth. The invention also includes host cells transformed by such DNAs, or vectors or plasmids containing such DNAs. A process for the production of isoprenoids and carotenoids using such transformed host cells is also provided.