Why is baker’s yeast useful for expressing genetically engineered genes?
The correct answer and explanation is:
Correct Answer:
Baker’s yeast (Saccharomyces cerevisiae) is useful for expressing genetically engineered genes because it is a eukaryotic organism that combines the advantages of simple genetic manipulation, rapid growth, and the ability to perform many post-translational modifications found in higher eukaryotes, making it an efficient and versatile host for protein expression.
300-Word Explanation:
Baker’s yeast, scientifically known as Saccharomyces cerevisiae, is one of the most widely used organisms in genetic engineering and biotechnology for expressing foreign genes. Its popularity stems from several key biological and practical advantages.
First, S. cerevisiae is a eukaryote, meaning its cellular machinery is similar to that of higher organisms, including humans. This allows it to correctly fold complex proteins and perform essential post-translational modifications such as glycosylation, phosphorylation, and disulfide bond formation, which many bacterial systems (like E. coli) cannot efficiently carry out. These modifications are crucial for the biological activity and stability of many proteins, especially those used in medicine and industry.
Second, baker’s yeast grows quickly and can be easily cultivated on inexpensive media, allowing large-scale production in bioreactors. Its genetics are well understood, with many tools available for precise genetic manipulation, including plasmids, promoters, and selectable markers, facilitating the stable insertion and controlled expression of engineered genes.
Third, yeast is generally regarded as safe (GRAS) for food and pharmaceutical applications, which simplifies regulatory approval for products derived from yeast expression systems.
Furthermore, yeast can maintain episomal plasmids or integrate genes into its genome, providing flexibility in gene expression strategies. It also tolerates the expression of toxic proteins better than bacterial hosts, expanding its utility.
Finally, decades of research on yeast genetics and metabolism provide a solid foundation for optimizing gene expression and fermentation conditions, making it a reliable and efficient platform.
In summary, Saccharomyces cerevisiae combines the genetic tractability and rapid growth of microorganisms with the complex cellular machinery of eukaryotes, making it an excellent host for expressing genetically engineered genes.