Biology · Biotechnology

DNA fingerprinting is a technique of determining nucleotide sequences of certain areas of DNA which are unique to each individual. The difference of about 0.1% or 3 × 106 base pairs (out of 3 × 10 9 bp) provides individuality to each human being. The human genome possesses numerous small noncoding but inheritable sequences of bases that are repeated many times. These sequences occur near telomere, centromeres, Y chromosome, and heterochromatic area. The area with the same sequence of bases repeated several times is called repetitive DNA. It is separated as a satellite from the bulk DNA during density gradient centrifugation and hence called satellite DNA where repetition of the bases is in tandem. Satellite DNAs show polymorphism (the occurrence of mutations in a population at high frequency), which is the basis of genetic mapping of human genome as well as DNA fingerprinting. While mutations in genes produce alleles with different expressions, mutations in noncoding repetitive DNA have no immediate impact. These mutations which have piled up with time form the basis of polymorphism.

DNA fingerprinting is not based on the relative proportions of purines (adenine and guanine) and pyrimidines (cytosine and thymine) in DNA. It focuses on specific DNA sequences.

While DNA can be obtained from blood, skin, and saliva for DNA fingerprinting, this option does not directly address the basis of DNA fingerprinting, which involves analyzing specific DNA sequences, not the source of the DNA.

This option is not related to the basis of DNA fingerprinting. It seems to refer to the physical impressions of fingerprints rather than the genetic analysis of DNA.

The basis of DNA fingerprinting is VNTR. VNTR is a satellite DNA as a probe showing a high degree of polymorphism. This implies that there are repetitive sequences of DNA that are found across individuals of all species. Scientists identify variations in these sequences.