Definition of Mutagenicity:
- Mutagenicity refers to a substance’s ability to cause changes (mutations) in the DNA of living organisms.
- A mutagen is an agent that can increase the frequency or extent of mutations beyond the natural background rate.
Types of Mutations:
- Point mutations: Changes in a single base pair (e.g., G to A).
- Frameshift mutations: Insertions or deletions that alter the reading frame of the gene.
- Chromosomal aberrations: Large scale rearrangements, deletions, duplications, or translocations.
Testing:
- Ames test: A classic bacterial assay (uses Salmonella typhimurium) to detect mutagenic potential of chemicals.
- Mammalian cell assays: Testing on cultured mammalian cells for chromosomal aberrations or micronucleus formations.
- Nitrosamines (such as NDMA): Found as impurities in some drugs (e.g., ranitidine) and are known mutagens, which led to drug recalls.
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Impact of Mutagenicity:
- Mutagenicity can lead to heritable genetic disorders (if the mutations occur in germ cells) or contribute to carcinogenesis (if they occur in somatic cells).
