Question:

Which aspect forms the basis of DNA finger- printing?

Updated On: Apr 17, 2024
  • The amount of DNA found in samples of blood, saliva and skin.
  • The ratio of purines and pyrimidines present in DNA.
  • The Sequence of DNA present in the ridges and grooves of finger-prints
  • The Satellite DNA showing high degree of repetition in DNA segments
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The Correct Option is D

Solution and Explanation

DNA fingerprinting, also known as DNA profiling or genetic fingerprinting, is a technique used to identify and analyze unique patterns in an individual's DNA. It relies on the presence of specific regions in the genome that exhibit high levels of repetitive DNA sequences known as satellite DNA. These repetitive sequences, such as short tandem repeats (STRs), are unique to each individual (except identical twins) and can be used to distinguish one person's DNA from another. 
The process of DNA fingerprinting involves isolating DNA from a sample (such as blood, saliva, or skin cells), amplifying specific regions of the DNA using polymerase chain reaction (PCR), and then analyzing the sizes and patterns of the amplified DNA fragments. By comparing the DNA fragment sizes and patterns between different individuals, it is possible to determine if they share a common genetic profile or if they are different. 
Therefore, it is the repetitive sequences, particularly satellite DNA regions, that serve as the basis for DNA fingerprinting and enable the identification and differentiation of individuals based on their unique genetic profiles.

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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.