The present invention is directed to a unicellular organism system, such as a yeast, for producing geranylgeranyl pyrophosphate and a diterpene in vivo. The yeast cell preferably comprises an inducible nucleic acid sequence encoding geranylgeranyl pyrophosphate synthase, an inducible nucleic acid sequence encoding a soluble form of HMG-CoA reductase, a nucleic acid sequence of an allele that confers an increase in sterol metabolic flux and, in the diterpene-producing cell, a diterpene synthase.