Saccharomyces cerevisiae is a species of budding yeast. It is perhaps the most useful yeast owing to its use since ancient times in baking and brewing. It is believed that it was originally isolated from the skins of grapes (one can see the yeast as a component of the thin white film on the skins of some dark-colored fruits such as plums; it exists among the waxes of the cuticle). It is one of the most intensively studied eukaryotic model organisms in molecular and cell biology, much like Escherichia coli as the model prokaryote. It is the microorganism behind the most common type of fermentation. Saccharomyces cerevisiae cells are round to ovoid, 5–10 micrometres in diameter. It reproduces by a division process known as budding.
It is useful in studying the cell cycle because it is easy to culture, but, as a eukaryote, it shares the complex internal cell structure of plants and animals. S. cerevisiae was the first eukaryotic genome that was completely sequenced. The yeast genome database  is highly annotated and remains a very important tool for developing basic knowledge about the function and organization of eukaryotic cell genetics and physiology. Another important S. cerevisiae database is maintained by the Munich Information Center for Protein Sequences . The genome is composed of about 13,000,000 base pairs and 6,275 genes, compactly organised on 16 chromosomes. Only about 5,800 of these are believed to be true functional genes. It is estimated that yeast shares about 23% of its genome with that of humans.
and that is it.
Do I care? No. I just enjoy the effects.