The Ames test identifies mutagenic chemical compounds by testing for increased r
ID: 201632 • Letter: T
Question
The Ames test identifies mutagenic chemical compounds by testing for increased reversion rates in auxotrophic bacteria exposed to a test compound in the pres liver In an experiment employing the methods of the Ames test, two his strains of Salmonella are used. Strain A contains a base substitution mutation, and Strain B contains a frameshift mutation. Four plates are prepared to test the mutagenicity of the compound ethyl methanesulfonate (EMS). Plate 1 is a control plate with Strain A and S9 extract but no EMS. Plate 2 is also a control plate and contains Strain B and S9 extract but no EMS. Plate 3 contains Strain A along with S9 extract and EMS, and Plate 4 contains Strain B, S9 extract, and EMS ence of detoxifying enzymes from the eukaryoticExplanation / Answer
Plate I = Strain A + S9 extract
Plate II = Strain B + S9 extract
Plate III = Strain A + S9 extract + EMS
Plate IV = Strain B + S9 extract + EMS
Plates I and II are control plates. They will have a relatively low number of colonies on the selection plate. They represent background SPONTANEOUS REVERSIONS.
Proflavin is a known mutagen (It is an intercalating agent) that induces FRAMESHIFT MUTATIONS.
So, plate IV will have more revertants (Since strain B is a frameshift mutant, it will show reversion to WT in the presence of Proflavin).
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