yeast

One of various single-celled fungi (see fungus) that form masses of tiny round or oval cells by budding. When placed in a sugar solution the cells multiply and convert the sugar into alcohol and carbon dioxide. Yeasts are used as fermenting agents in baking, brewing, and the making of wine and spirits. Brewer's yeast (S. cerevisiae) is a rich source of vitamin B. (Especially genus Saccharomyces; also other related genera.)

In April 1996 the sequencing of the genome of S. cerevisiae was completed, following six years of research by 300 scientists. S. cerevisiae has over 12 million base pairs and approximately 6,000 genes, the function of 40% of which are yet to be identified.