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Single cell of yeast has 3 to 5 microns in diameter. Visible colonies of yeast are composed of at least one million cells. Package of yeast used for cooking contains billions of cells.
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Like in other eukaryotic organisms, DNA of yeast is located inside the nucleus. Yeast also contains mitochondria, organelles responsible for the manufacture of energy.
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25% of the yeast's genes can be found in human genome.
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Anton van Leeuwenhoek saw the cells of yeast under the microscope in 1680, but he failed to identify them as living entities. Nearly two centuries later (in 1857), Louise Pasteur discovered that cells of yeasts are responsible for the brewing of beer (instead of chemical catalyst, as the people believed back then).
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Yeast converts sugar from liquid medium into alcohol and carbon dioxide and improves aroma of beer and wine. It was used for making of beer and wine thousands of years before it was discovered.
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Yeast can change taste and smell of beer in hundreds of ways (it can produce 600 different compounds that affect flavor and aroma of beer).
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Yeast plays important role in the manufacture of bread and various dough.
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Ancient Romans learned that dough left in the sun can be "revived" after adding the sugar. Without knowing it, they discovered the yeast.
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Brewer's yeast is often used as food supplement due to high content of vitamins of the B group.
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Brewer's yeast is used as model organism in the laboratories around the world. Molecular pathways and genetics of brewers' yeast are vital for understanding of mechanisms of aging of eukaryotic cell. 20 genes that determine the exact lifespan of the yeast have been discovered by the year 2000.
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Some species of yeast can induce various diseases in humans and animals. Candida albicans, for example, can induce infection in the mouth and gastrointestinal tract of humans.
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Yeast is frequently used in the industry of biofuel (for the manufacture of ethanol) and for degradation of oils, explosive materials, hydrocarbons and fatty acids in the polluted areas.
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Most species of yeast reproduce asexually. Yeast forms buds, small protrusions on one side of the cell that grow in size, mature and eventually detach from the mother cell. This type of reproduction is called asymmetric division.
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In some species of yeast, mother cell divides in two equal daughter cells. This is known as fission.
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Yeast cell has an average lifespan of few days.
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