During the investigation of forensics, the unique nucleotide sequences in the DNA molecule are obtained from organisms which are genetically similar to each other. This is called DNA fingerprinting. British geneticist ALEC Jeffreys was the first person who developed the method of DNA fingerprinting. He isolated images of DNA and made images of them. The cells are which are used for DNA fingerprinting can be taken from different parts of the body for example, skin cells, hair cells and blood cells. The DNA is extracted from these cells and is purified. Specific enzymes are used to cut the DNA in small pieces. These small pieces are then put under observation and analyzed. Different individuals have different patterns of fragments. These patterns show the identification of the person. DNA fingerprinting is used to identify criminals, even the paternity of a child can also be known with this technique. Scientists have identified various genetic diseases by using the method of DNA fingerprinting. The plants which are resistant to the drought can also be identified through DNA fingerprinting. DNA fingerprinting is also known as DNA typing.
There are some regions in molecule of DNA which have non-functional properties. This part of the DNA consists of long stretched sequences which are repeated with the bases of DNA that is A, G, C, T. though these parts are non-functional but still there is some order in their sequences for example some such type of regions are called as mini satellite DNA. This type of DNA contains mini sequences in the repeated from. Up till now, 100 such regions have been found in the human genome, these all regions are related to the genes which are involved in protein coding. As we already know that every human being has different genetic makeup, so all these regions vary from person to person. These regions do have some unique genetic profile or fingerprint. As these region are dispersed in the genome randomly that is why they have different locations in different individuals' genome.
Method to obtain a DNA Fingerprint:-
There is a specific method through which DNA fingerprints are obtained.
1) Cells from some part of the body for example from skin or hair are taken. DNA found at the root of the hair is more than enough for DNA fingerprinting.
2) DNA molecule taken is digested with the special kind of enzymes which are called as restriction enzymes. These enzymes cut the DNA into pieces at specific places and make small fragments. By using the technique of electrophoresis, cut DNA pieces are sorted and then are passed from the seaweed agarose gel. This technique of cutting the DNA and making pieces of it is similar to the biotechnology technique of screening to determine the size of the particles.
3) The DNA fragments which are separated are dispersed on the nylon sheet which is soaked in the agarose gel.
4) DNA probes are usually colored to identify the specific sequences in the DNA molecules. These colored or radioactive probes are then also dispersed on the nylon sheet. Each probe will find its complementary strand and will stick to it.
5) Through these steps, the DNA fingerprints are obtained which can be used for various purposes.
There are many uses of DNA fingerprinting. DNA fingerprinting can also used to detect genetic diseases in parents and also in the newborns. Genetic diseases like cystic fibrosis, hemophilia, sickle cell anemia are identified through DNA fingerprinting. The information present on the DNA fingerprints enables the scientists to know about the specific genetic disease. Scientists study the genetic makeup of the parents of the child or relatives and then they make special methods to cure that disease.
DNA fingerprinting for identifying the criminals has been used by the FBI and other police departments in the world to identify the criminals. The evidence found from the crime scene such as, blood, hair or any other skin cells makes police find the real culprit of the crime.
In court, DNA fingerprinting is used to establish paternity of the child. Because DNA fingerprints give the accurate results about the relationship of the child to the parents.
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