Yeast

Yeasts are rising stars in the toolbox of biotechnologists. Early in the development of biotechnology, which used cells as recipients of transplanted genes, bacteria were the organism of choice. However, limitations involving differences between bacterial cells and our own have relegated bacteria to a second place behind yeasts. Both yeast cells and human cells are eukaryotic—possessing a nucleus and membrane-bound organelles such as ribosomes and mitochondria. As biotechnology techniques have progressed over the last decade, yeasts have come to the fore as host cells for human gene implantation and as potential surrogate cells for housing human chromosomes. Yeasts have also been subjected to the alteration of their own genes, as biotechnologists attempt to develop strains of yeast more efficient in the metabolism of sugars for food and industrial applications.

By studying yeast genetics, scientists hope to gain insight into how the genes of all eukaryotic cells, including our own, function. In 1993 the first yeast chromosome was completely mapped, and the function of each of the 182 genes has yielded insight into such vital genetic processes as mutation repair, enzyme production, and cellular division regulation. These findings may yield insights into such fundamental human health issues as cancer and the aging process. Yeasts have also been transformed through genetic engineering to produce the first genetically engineered vaccine for hepatitis B. Insulin and hemoglobin are also being commercially manufactured by yeast cells which have been re-coded by inserted human genes. Yeasts are a hopeful host cell for housing the entire human genome in an international effort to decipher the gene library of human cells.