a) DNA Polymorphism: If an inheritable mutation is observed in a population at a high frequency it is called DNA Polymorphism. This polymorphism ranges from a few nucleotides to very scale changes. DNA polymorphism, may create or destroy restriction enzymes recognition sites. As a consequences, the pattern of restriction fragment length from a region of the genome may differ between homologous chromosomes and between two individuals. Through the information on polymorphism of restriction endonuclease restriction site genetic mapping of human genome was done.
b) The most important fact for DNA-fingerprinting are the short nucleotide repeates, called variable number Tandem Rpeats (VNTRs), they very in number from person to person to person and are inherited. The VNTRs of two persons may be of same length and sequence at certain sites, but very at others. These VNTRs are hybridized with labeled VNTR probes and an autoradiogram of bands of different sizes is generated.
