Talk:Auxotrophy

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There should be a section added explaining the importance of auxotrophy in the Ames Test. Since the Salmonella are unable to produce their on histidine, i.e. they have an auxotrophic mutation his-, they cannot grow unless they are grown on a medium containing histidine. Chemical compounds, such as cosmetics, preservatives and medications are added to the Salmonella, and they are then attempted to be grown on a medium defficient in his. The amount of colonies that grow are indicative of the mutations that allow them to once again produce histidine. Some colonies will spontaneously mutate due to errors in replication, but the ratio of Salmonella colonies grown on histidine lacking medium that have not been mixed with the compound to those that have been mixed provides a reliable way to measure the mutagenicity of a substance. The auxotrophic mutatants, have transitions, transversion and frameshift mutations that are easly correctable with a simple point mutation to allow for the production of histidine once again. 74.114.161.86 19:00, 14 February 2007 (UTC)

Oops, sorry, the above paragraph was from me; I forgot to sign in. Silver 19:01, 14 February 2007 (UTC)