Definition of Mutant Allele
Mutant allele is such an allele on which mutation has occurred. The genetic makeup of an organism is composed of long chains of nucleotides that result in the formation of DNA molecules. Any change that occurs in the structure of these molecules can alter the function of it.
A gene generally has two regions i.e. regulatory and a coding region. The former one regulates the transcription machinery whereas the coding region is responsible for carrying the genetic code for the molecular structure.
The mutation can lead to the incorrect substitution of a base or can delete or insert a base pair. In these ways, the mutant alleles are produced which stop the protein synthesis or incorporate a wrong amino acid in the structure of the protein. Hence, the mutant alleles are incapable of producing the same level of active product as compared to the wild-type allele.