Chemically defined medium | Wikipedia audio article
Channel: wikipedia tts
Date: 2019-06-07

This is an audio version of the Wikipedia Article:
https://en.wikipedia.org/wiki/Chemically_defined_medium


00:02:45 1 The advantages of chemically defined media
00:04:32 2 Classes of media
00:05:42 3 Misuse of the term chemically defined media
00:06:47 4 Other variants of serum-free/defined media include
00:07:21 5 See also



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SUMMARY
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A chemically defined medium is a growth medium suitable for the in vitro cell culture of human or animal cells in which all of the chemical components are known. Standard cell culture media commonly consist of a basal medium supplemented with animal serum (such as fetal bovine serum, FBS) as a source of nutrients and other ill-defined factors. The technical disadvantages to using serum include its undefined nature, batch-to-batch variability in composition, and the risk of contamination.
There is a clear distinction between serum-free media and chemically defined media. Serum-free media may contain undefined animal-derived products such as serum albumin (purified from blood), hydrolysates, growth factors, hormones, carrier proteins, and attachment factors. These undefined animal-derived products will contain complex contaminants, such as the lipid content of albumin. In contrast, chemically defined media require that all of the components must be identified and have their exact concentrations known. Therefore, a chemically defined medium must be entirely free of animal-derived components and cannot contain either fetal bovine serum, bovine serum albumin or human serum albumin. To achieve this, chemically defined media is commonly supplemented with recombinant versions of albumin and growth factors, usually derived from rice or E. coli, or synthetic chemical such as the polymer polyvinyl alcohol which can reproduce some of the functions of BSA/HSA.
The constituents of a chemically defined media include: a basal media (such as DMEM, F12, or RPMI 1640, containing amino acids, vitamins, inorganic salts, buffers, antioxidants and energy sources), which is supplemented with recombinant albumin, chemically defined lipids, recombinant insulin and/or zinc, recombinant transferrin or iron, selenium and an antioxidant thiol such as 2-mercaptoethanol or 1-thioglycerol. Chemically defined media that are designed for the cultivation of cells in suspension additionally contain suitable surfactants such as poloxamers in order to reduce shear stress caused by shaking and stirring.