DNA Fingerprinting is carried out in order to examine and
estimate the familial relationship between two members of a family or between
two people. In Microbial studies it is carried out to identify the causative
organism of the disease by identifying its genetic material that is., DNA. In
Forensic studies DNA Finger printing is done to solve critical crimes in
criminal investigations wherein from the evidences and blood samples the
criminal is identified using this technique because enough DNA is contained in
a minimal drop of blood or in root of hair. DNA fingerprinting in Forensic
terms is called as DNA profiling.
a very simple principle involved in DNA finger printing every individual has
DNA as their genetic material inherited from their parents. This DNA is
involved in the production of particular
proteins needed for life based on the codon sequence additional to this they
contain a particular DNA section which is unique to that individual. Just like
our finger prints which is unique to each and every one that is finger print of
one individual never matches with the other, similarly these sections of DNA of
one individual doesn’t match with the others a section is inherited from their
parents and this is helpful to identify the relationships. When DNA finger
printing is carried out with the motive of species identification not an
individual is called as DNA barcoding.
numerous steps involved in DNA finger printing for the aquishion of results
with precision and accuracy.
DNA is present in every part of the body so
collection of sample is an easy step. Mostly used sources to collect the
samples is blood , roots of hair and buccal swap is also advisable
Generally in most of the situations the DNA
available is minimal for instance in criminal investigations, so in order to
obtain enough DNA for testing the Polymerase Chain Reaction (PCR) is carried
out where in the DNA undergoes rapid replication and results in more DNA, the main motive of this step is to improve
the amount of DNA for the test.
isolated and increased amount of DNA obtained is taken to the next step in
which a few enzymes named Restriction Enzymes are involved. These Enzymes have
the ability to break the DNA at very specific and accurate sites with high
degree of accuracy. On treatment with the Restriction Enzymes it will result in
the breakage of the DNA into numerous tiny fragments of varies sizes
broken fragments should undergo fine separation. This is achieved by performing
an Agarose Gel Electrophoresis in which the fragmented pieces of DNA by
restriction Enzymes gets separated based on their size. DNA is charged
negatively so moves towards the positive electrode and the fragments hence gets
separated based on the size.
These separated fragments are taken out using a
nylon membrane BY the simple sieving process. Treatment with chemicals is done
in order to make the DNA single stranded.
Next step involves the crosslinking of the DNA
which is single stranded with the nylon with the help of heat, process is a
kind of similar to the Backing process or using Ultraviolet Rays.
Decaying of the DNA strand occurs and the light
is given this results in the showing up of the probe. Finally we can find Dark
spots on the film which actually is nothing but the unique DNA band of the
person the band pattern is unique and different from one person to another
because we are all unique.
On exposure of this film to the x ray
radioactive DNA sequence which even a nacked eye can detect is obtained. A
banding pattern called as DNA fingerprint is obtained.
The DNA finger
print of a child is unique but there should be similarity between some of the
bands of the child with her parents some of her bands matches with one parent
where as some of the bands should match with the other parent. The main use of
this technique is carried out for the identification of the biological parents
of a child whose parents claim is wrong. There are various other applications
of DNA finger printing also. It is said that the similarity of DNA between two
humans is nearly 99.9% that 0.01% difference gives the uniqueness to every individual.
This sequence which shows uniqueness is generally designated as Minisatellites.
But in case of identical twins it is generally not possible to carry out this
process because they are totally genetically similar. DNA Finger Printing is a
very interesting and applicable tool in crime investigations and biological
tests but there are a few oppositions to this tool. DNA finger printing is strictly
limited only to few cases for the sake of privacy to the individual.