Question:

The basis of DNA finger printing is .........

Updated On: Jun 21, 2022
  • Knowledge of electrophoresis
  • Knowledge of human karyotype
  • Phenotypic difference in individuals
  • Occurrence of restriction fragment length polymorphism
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The Correct Option is D

Solution and Explanation

Genetic or DNA fingerprinting, DNA testing or DNA profiling is the technique used to distinguish between individuals of the same species using only samples of their DNA. It was invented by Sir Alec . Jeffreys. Variable Number of Tandem Repeat (VNTR) polymorphism is the basis of DNA fingerprinting which are short nucleotide repeats. The location and repetition in VNTR is so unique that no two individuals are alike. During DNA fingerprinting special DNA probes (single stranded labelled DNA rands) which with known sequences of probes complementary to these on VNTRs are used which bind to these VNTRs and make . them radiolabelled and thus observable. DNA fingerprinting may also use RFLP. DNA of each organism has specific sequences calle restriction fragments that can be cleaved by restriction endonuclease enzymes to produce fragments of different lengths. Occurrence of different lengths of cleaved DNA sequences is referred to as restriction fragment length polymorphism (RFLP).
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Concepts Used:

DNA Fingerprinting

​​DNA fingerprinting, also called DNA typing, DNA profiling, genetic fingerprinting, genotyping, or identity testing, in genetics, method of isolating and identifying variable elements within the base-pair sequence of DNA.

The procedure of DNA Fingerprinting:

The procedure for creating a DNA fingerprint consists of first obtaining a sample of cells, such as skin, hair, or blood cells, which contain DNA. The DNA is extracted from the cells and purified. In Jeffreys’s original approach, which was based on restriction fragment length polymorphism (RFLP) technology, the DNA was then cut at specific points along the strand with proteins known as restriction enzymes. The enzymes produced fragments of varying lengths that were sorted by placing them on a gel and then subjecting the gel to an electric current (electrophoresis): the shorter the fragment, the more quickly it moved toward the positive pole (anode). The sorted double-stranded DNA fragments were then subjected to a blotting technique in which they were split into single strands and transferred to a nylon sheet. The fragments underwent autoradiography in which they were exposed to DNA probes—pieces of synthetic DNA that were made radioactive and that bound to the minisatellites. A piece of X-ray film was then exposed to the fragments, and a dark mark was produced at any point where a radioactive probe had become attached. The resultant pattern of marks could then be analyzed.