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Ames Test

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- What is an Ames Test?

- 3 discs were impregnated with either a control substance, chemical 1, or chemical 2 and placed on a lawn of his- Salmonella grown on medium that does not contain histidine supplement (think: would you expect this strain of Salmonella to grow on plates without histidine?). Attached are the results after incubating the plates for 2 days at 37 degrees Celsius. In a few words, describe the results for the control and chemicals 1 and 2.

- Which chemical would you NOT recommend as a sunscreen additive and why?

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- What is an Ames Test?

Ames test is a test to determine if a " chemical is a mutagen." (1) It is a test developed by Bruce Ames to evaluate the mutagenic properties of the bacteria. The test typically uses strains of bacteria that are histidine dependent and required histidine to grow. The bacteria will not grow in the absence of histidine. However, the presence of a mutagen will allow the his- mutant bacteria to revert back to the normal phenotype allowing bacteria to grow on His- plate. The mutagen molecule cause an increase in the revertant colonies relative to the background level.
The bacteria strain is inoculated into the bacterial culture medium lacking histidine or any other nutrient that the bacteria strain cannot grow without. The bacterium used in the Ames test is a strain of Salmonella typhimurium that have a defective gene making it unable to make the amino acid histidine ( His -) strain of S. typhimuium is plated on plate lacking histidine. The filter disk of paper has chemicals that is potentially a carcinogen. It is thought that the ...

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Ames test is a test to determine if a " chemical is a mutagen." (1) It is a test developed by Bruce Ames to evaluate the mutagenic properties of the bacteria. The test typically uses strains of bacteria that are histidine dependent and required histidine to grow. The bacteria will not grow in the absence of histidine. However, the presence of a mutagen will allow the his- mutant bacteria to revert back to the normal phenotype allowing bacteria to grow on His- plate. The mutagen molecule cause an increase in the revertant colonies relative to the background level. It is a test to determine if the bacteria is a mutagen.

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12) What do you understand by the term biological half time?

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