The Physics Factbook
Edited by Glenn Elert -- Written by his students
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|Tortora, Funke, & Christine L. Case. Microbiology: An Introduction.California: Benjamin Cummings, 1998: 322-23.||[diagram]||10 µm|
|"Yeast." McGraw-Hill Encyclopedia of Science and Technology. 8th ed. Pennsylvania: McGraw Hill, 1997.||"The diameter of a spherical cell may vary from 2 to 10 micrometers. The length of cylindrical cells is often 20-30 micrometers and in some cases, even greater."||2-10 µm
|Pasarell, Lester. Blastomycosis. Medical Mycology. University of Texas Medical Branch.||"The yeast cells are globose to ovoid in shape and approximately 8-15 um in diameter."||8-15 µm|
|Harrison, Rose & J. S. Biology of Yeast. London: Academic Press, 1969: 10-18.||[diagram]||10 µm|
|Kaiser, Gary E. Biol 230 Lab Manual, Lab 1. Community College of Baltimore County. 29 May 2000.||"Yeasts, such as the common baker's yeast Saccharomyces cerevisiae, are unicellular fungi. They usually appear spherical and have a diameter of 5-10 µm. Yeasts commonly reproduce asexually by a process called budding."||5-10 µm|
|Volk, Thomas J. Tom Volk's Fungus of the Month for January 2000. University of Wisconsin, Madison.||"When inhaled into the alveolar spaces it is primarily the microconidia that germinate and then transform into small budding yeasts 2-5 um diameter."||2-5 µm|
YEEEEEast!!! hehehehe!!! =0)
Yeast have many important ecological and economic roles. Yeast are single celled organisms that belong in the group of simple organisms called "Fungi,"which exist almost everywhere in nature, including the air. They can be found in the ecosystem and in millions of kitchen around the world. Although there are 6 hundred types of yeast, only a few cause diseases in plants, animals, and humans; and only a few are use commercially. Most yeast lives in soil, on plants surfaces, and on decaying organic matter.
An average yeast cell is 4 to 12 micrometers (µm) long. The measurements for the diameter of a yeast are diverse because there are about 6 hundred different species of yeast in the world. Each type of yeast come in different sizes, so as a result the diameters are just estimates of some of the more common yeasts. The majority of the yeast are ascomycetes. Ascomycetes are any of various members of a large group of fungi characterized by the presence of sexually produced spores formed within an ascus.
Yeasts reproduce rapidly. They grow especially well in substances containing sugar. Yeast cells reproduce by fission (splitting in two) or by budding. In budding, part of the cell wall of the yeast swells and forms a new growth called a bud. The bud then breaks off and becomes an independent cell. Most yeast reproduce by budding and all have the ability to ferment sugars. Yeasts are a rich source of protein and vitamins. The average diameter of a bud scar is approximately 1 µm with a ring thickness of about 0.2 µm.
Yeast are among the first domesticated "animals." They had been in use ever since the agricultural revolution. There are two major industries that revolve around the use of yeast and their metabolic products. These two industries are the baking and alcohol industry. The yeasts used commercially consist of masses of microscopic yeast organisms. Bakers put yeast in dough to make it rise and it is also used in the production of beer, wine, and other alcoholic beverages.
Yeast are a big part of our society. They both help and harm the society, but without them we wouldn't be able to function effectively.
Jenny P. Ng -- 2000
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