An illustration of the impressive development of yeast gene expression systems accomplished in recent years which demonstrates the power of these systems for the production of proteins in quantities useful as therapeutics, industrial enzymes and research agents. It provides a foundation for the comprehensive study of the molecular biology of yeast and describes and reviews many basic aspects of yeast biochemistry and cell biology at the DNA, RNA and protein levels. The book covers, at the molecular genetic level, processes involved in the natural metabolism and propagation of yeasts. In addition, it superimposes the modern methods of molecular biology and biotechnology on this background of classical information. The first recombinant subunit vaccine against hepititis B, for example, is manufactured from genetically engineered yeast.