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Yeast (Saccharomyces cerevisiae)

The yeast is perfect for genetic studying and engineering because it has the cellular organization of a eukaryote, but it is pretty simple single-celled organism that is easy to grow and manipulate genetically. Since they are from the same kingdom as us humans, the study of their cell cycle, and the control of cell cycle and cell division has given us the insight into our own. This is possible since there are approximately 6000 different proteins expressed in yeast whose homologs are found in almost all eukaryotes.

Basically, most of what we know of the proteins in the endoplasmic reticulum and Golgi apparatus has been found out with the help of yeast. It has also been studied for protein secretion and membrane biogenesis, as well as for the function of cytoskeleton. Cell differentiation and aging is also an interesting process, especially for humans, and we have found a lot about it studying yeast. If we go down to genetic level, gene regulation and chromosome structure is also the target for genetic experiments in S. cerevisiae.

Yeast is popular since vast numbers of yeast cells can be grown easily and cheaply from a single cell, resulting in completely identical colony of cells with same biochemical properties, making it great for purification of proteins and their study in detail. Moreover, yeast cells can grow by mitosis both as haploids and diploids (containing one and two copies of each chromosome, respectively), which makes it easy to isolate and characterize mutations in genes which encode essential cell proteins.

Yeast, like many organisms, has a sexual cycle, which allows exchange of genes between cells. Interesting thing happens under starvation conditions – diploid cells undergo meiosis, making two different haploid cells from a single diploid one (a and α). These can then grow by mitosis and if they encounter each other, they can fuse forming a/α diploid. This mechanism gives us a lot of possibilities to perform some additional genetic experiments.