The Ames test ___________.


a. uses auxotrophs and liver extract to reveal mutagens
b. s time intensive and costly
c. involves the isolation of a mutant by eliminating wild-type phenotypes with specific media
d. proves that suspected chemicals are carcinogenic

Verified step by step guidance

1. Understand the purpose of the Ames test: it is a biological assay used to assess the mutagenic potential of chemical compounds by observing whether they cause mutations in the DNA of certain bacteria.
2. Recall that the Ames test uses auxotrophic strains of bacteria, which are mutants that cannot synthesize a particular nutrient (often histidine) and require it to be supplied in the medium.
3. Recognize that the test includes the use of liver extract (S9 mix) to simulate mammalian metabolism, as some chemicals become mutagenic only after metabolic activation.
4. Note that the test detects mutagens by measuring the rate at which the auxotrophic bacteria revert to prototrophy (ability to grow without the supplemented nutrient), indicating mutation.
5. Evaluate each answer choice based on these points: the correct description should mention the use of auxotrophs and liver extract to reveal mutagens, rather than claiming the test is time intensive, isolates mutants by eliminating wild types, or proves carcinogenicity directly.

Key Concepts

Ames Test Purpose and Principle

The Ames test is a biological assay used to detect chemical substances that cause mutations in DNA, indicating potential mutagenic and carcinogenic properties. It uses specially engineered bacteria to reveal whether a chemical can induce genetic mutations.

Use of Auxotrophic Bacteria and Liver Extract

The test employs auxotrophic strains of bacteria that cannot grow without a specific nutrient unless a mutation restores this ability. Liver extract is added to simulate mammalian metabolism, which can activate pro-mutagens into mutagens, making the test more relevant to human exposure.

Interpretation and Limitations of the Ames Test

While the Ames test indicates mutagenic potential, it does not definitively prove carcinogenicity in humans. It is a rapid, cost-effective screening tool but requires further testing to confirm cancer risk, as not all mutagens cause cancer and vice versa.