Yeast Basics

 

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S. cerevisiae was first established as a tool for genetic studies in the 1930's and 40's - nearly 100 years after Mendel performed the first controlled genetic experiments on pea plants. By the end of the 20th century, S. cerevisiae was (and still is!) widely accepted as one of the most powerful model systems for the study of genetics and biochemistry.

One of the qualities that make S. cerevisiae particularly suitable for genetic research is that it is a unicellular microbe. Its small size makes easy to care forů no large, smelly cages to clean and maintain. Perhaps more importantly, S. cerevisiae is eukaryotic (as all Fungi are) and thus yeast cells share much in common with human cells, unlike single-celled bacteria (also known as prokaryotes). Yeast also have many well-characterized genetic markers; the yeast genome contains relatively little "junk DNA" (repetitive sequences, introns, etc.); yeast cultures grow rapidly and can be readily transformed with plasmids; mutants in many processes are easy to identify and isolate; and when frozen under the appropriate conditions, yeast remain viable and genetically stable for years, perhaps indefinitely. Furthermore, S. cerevisiae can be maintained in the haploid or diploid state, thereby expanding the possibilities for genetic research by making it easier to study both recessive alleles and genes essential for life.

One of the greatest advances in yeast genetics occurred in 1996 when a global consortium finished sequencing the genome of S. cerevisiae (the first eukaryotic genome to be completed!). The results of this sequencing effort revealed that the 16 chromosomes of S. cerevisiae harbor about 6,200 potential protein-encoding genes (also known as open reading frames, or ORF's), nearly 40% of which have obvious homologues in other eukaryotic organisms. At that time, less than half of the yeast ORF's identified were being studied, and even today, hundreds remain poorly characterized or have no known function.

In addition to providing a detailed genetic map, this sequencing triumph helped usher in the era of genomics. Instead of being limited to the study of one or a few genes, researchers developed techniques to study changes in the expression levels of thousands of genes simultaneously.

On this site, you will find a variety of resources for using S. cerevisiae in the classroom, in "wet" labs, and in computer labs.  Additional background information is provided for students and non-yeast geneticists.  Combined, this information demonstrates how "awesome power of yeast genetics" can impact undergraduate science education.

Next:  The Lifecycle of Yeast

 

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