Question

Mention how DNA polymorphism arises in a population.

Answer 1

Hint: A variation in the DNA sequence which is not associated with any observable phenotypic variation is referred to as DNA polymorphism. DNA fingerprinting as well as genetic mapping of the human genome is based on DNA polymorphism.

Complete answer: The reason for the polymorphism is mutation. In an individual, the occurrence of new mutations may either be in the somatic cells or in the germ cells. If an individual’s ability to have offspring who can transmit the mutation is not seriously impaired by germ cell mutation, it will spread to the other members present in a population. This can take place via sexual reproduction.
Allelic sequence variation is the occurrence of more than one variant or allele at a locus in the human population with a frequency greater than 0.01. This variation is referred to as DNA polymorphism.
Hence, in a population, if the frequency of inheritable mutation is high it is defined as DNA polymorphism. In DNA which has non-coding sequences, there is a higher probability that this type of variation will occur. This is because mutations in these sequences do not immediately affect an individual’s ability to reproduce. The basis of polymorphism is formed by the accumulation of these mutations for generation after generation.

Note: DNA polymorphism can be used for analysis and molecular genetic studies because it can be used as a genetic marker. Since polymorphism can be a single nucleotide change or a very large-scale change, it can play an important role in evolution and speciation.