The following sections of this BookRags Literature Study Guide is offprint from Gale's For Students Series: Presenting Analysis, Context, and Criticism on Commonly Studied Works: Introduction, Author Biography, Plot Summary, Characters, Themes, Style, Historical Context, Critical Overview, Criticism and Critical Essays, Media Adaptations, Topics for Further Study, Compare & Contrast, What Do I Read Next?, For Further Study, and Sources.
(c)1998-2002; (c)2002 by Gale. Gale is an imprint of The Gale Group, Inc., a division of Thomson Learning, Inc. Gale and Design and Thomson Learning are trademarks used herein under license.
The following sections, if they exist, are offprint from Beacham's Encyclopedia of Popular Fiction: "Social Concerns", "Thematic Overview", "Techniques", "Literary Precedents", "Key Questions", "Related Titles", "Adaptations", "Related Web Sites". (c)1994-2005, by Walton Beacham.
The following sections, if they exist, are offprint from Beacham's Guide to Literature for Young Adults: "About the Author", "Overview", "Setting", "Literary Qualities", "Social Sensitivity", "Topics for Discussion", "Ideas for Reports and Papers". (c)1994-2005, by Walton Beacham.
All other sections in this Literature Study Guide are owned and copyrighted by BookRags, Inc.
Yeast is a unicellular fungus. There are many different species of yeast, but the majority of them are acomycetes. They all reproduce by a process of budding and they all have the ability to ferment sugars. Yeasts are a rich source of protein and vitamins, particularly of the B complex. There are two main industries that revolve around the use of yeast and their metabolic products. The first of these industries is baking, where carbon dioxide from the breakdown of sugar bubbles through the dough, making the bread rise. The second industry is the alcohol industry where the sugar is turned to alcohol by the action of the yeast.
One of the most common species encountered both in bread and alcohol production is Saccharomyces cerevisiae. Historically, this species has also been used in genetic research; it contains 17 linkage groups, which have some 150 known mutants associated with them. Mitochondrial mutants have also been extensively studied. Many other species of yeast exist and some companies have their own species that they use for the production of alcohol. (Different yeasts supposedly impart radically different tastes to alcohol.)
Yeasts are not a formal taxonomic group, but a growth form shown by a widely unrelated group of organisms. Some filamentous forms of fungi will show a yeast form under certain conditions. There are between five and six hundred species of yeast.