Q70. Ames test is performed to detect
- Mutagen
- pH
- Nutrient stress
- Salinity
Ames Test: Detects Mutagens in Q70 MCQ Explained
The Ames test is a key microbiological assay primarily used to detect mutagens. In Q70, the correct answer is Mutagen.
Correct Answer
Mutagen is the right choice for Q70. Developed by Bruce Ames, this test screens chemicals for mutagenic potential using histidine-requiring Salmonella typhimurium strains. Mutagens cause reverse mutations, allowing bacterial growth on histidine-free media, indicating DNA damage.
Test Principle
The Ames test exploits auxotrophic bacteria unable to synthesize histidine due to specific gene mutations. Exposure to a potential mutagen induces revertant mutations, restoring prototrophy and colony formation. It includes rat liver extract (S9) for metabolic activation of pro-mutagens.
Why Other Options Are Incorrect
Option Explanation pH The test may use pH indicators in variants like Ames MPF for color change detection from bacterial growth, but it does not detect or measure pH levels. Nutrient stress While histidine limitation creates auxotrophy, the test identifies mutation reversal under minimal media, not general nutrient stress assessment. Salinity No role in salinity detection; the assay focuses on genotoxicity in standard media without salt stress components. Applications and Limitations
Primarily screens drugs, pesticides, cosmetics, and environmental samples for carcinogenicity risk, as many mutagens are carcinogens. Limitations include missing eukaryotic-specific effects and false positives/negatives.
