Summary
A single-celled fungus used in baking and brewing that ferments sugars into carbon dioxide and ethanol.
In depth
Saccharomyces cerevisiae ferments sugars. In bread, CO2 makes dough rise and ethanol evaporates; in brewing and winemaking, ethanol is the product. It buds asexually and is a key model eukaryote: the first eukaryotic genome sequenced (1996).
Yeast reproduce by budding. They ferment glucose even with oxygen (Crabtree effect). Genetic tools make yeast a model for eukaryotic cell biology and a biotech chassis.
Remember: yeast are fungi, not bacteria.
Yeast is a single-celled fungus and the first eukaryote with a fully sequenced genome (1996, 12 million base pairs and about 6000 genes). It is a model for the cell cycle (Hartwell, Nurse), autophagy (Ohsumi) and secretion (Schekman). It can grow with or without oxygen: with it, yeast respires fully, without it, it ferments to ethanol and CO2, and glucose promotes fermentation even with oxygen (Crabtree effect).
Uses include beer, wine, bread, biofuel ethanol and production of recombinant proteins such as insulin and hepatitis B vaccine. Synthetic yeast chromosomes are being built in the Sc2.0 project. Candida species are related yeasts that can be pathogenic.
Example: baker's yeast makes bread rise because CO2 bubbles are trapped in gluten.
Frequently asked questions
What is Yeast?
A single-celled fungus used in baking and brewing that ferments sugars into carbon dioxide and ethanol.
Which area of biology covers Yeast, and how advanced is it?
Yeast is one of the 54 topics in Microbiology. It is rated Beginner, so it suits learners who are starting out in biology. Related topics in this area include Bacteria, Fermentation, Microorganisms.
Can you give an example of Yeast?
Yeast cell cycle genes discovered by Hartwell and Nurse (Nobel 2001).
What should I learn before Yeast?
Yeast is a Beginner topic, so no earlier topic is required. Other Beginner topics in Microbiology that pair well with it include Microorganisms, Bacteria, Archaea.
What topics are related to Yeast?
The closest topics to Yeast are Bacteria, Fermentation, Microorganisms, Fungi. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Yeast?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Yeast. To practise the whole of Microbiology, use the Microbiology quiz.
How is Yeast different from Bacteria?
Yeast: A single-celled fungus used in baking and brewing that ferments sugars into carbon dioxide and ethanol. Bacteria: Single-celled prokaryotes found everywhere, vital for nutrient cycling, digestion and some disease. Read both side by side and note what each one explains.
How should I study Yeast step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Bacteria and explain the difference aloud. Finally, take the Microbiology quiz and come back to this page for any question you miss.