DNA Tests Revealed the Mystery of Identity

The number of victims of an accident not intact, such as an airplane crash or the victims of a crime, it will certainly complicate the process of identification of the victims. Identification of the common techniques is the identification of fingerprints or dental structure, identification. But if the condition of victims who want to be identified really was already destroyed, usually the last option is to conduct DNA tests. This DNA test is a molecular biology technique used for the purposes of forensic material to be tested, based on his DNA profile. 

This technique is also known as DNA fingerprinting or DNA profiling. The technique invented and developed in 1984 by British geneticist Sir Alec Jeffreys, from University of Leicester, and first used to convict Colin Pitchfork in 1988 in the Enderby murders case in Leicestershire, England. 

DNA (Deoksiribo Nucleic Acid) is the genetic material contained within the body cell's nucleus or the mitochondria of each person, who inherited from his parents. DNA can be regarded as a blueprint for all cell activity, as the coder to determine the hair color, eye shape, face shape, skin color, and so forth. DNA is a polymer consisting of a phosphate group, sugar deoksiribo, and four types of nucleotide bases, namely adenine (A), guanine (G), cytosine (S), and thymine (T). Sequence of bases in DNA molecules specific, determining the genetic information. Complementary strands of DNA structure shows base pairs (adenine with thymine and guanine with cytosine), forms a double spiral (double helix). The sequence of bases in DNA molecules that determine the genetic information contained within it. In summary, the sequence of these bases determines everything about a person such as hair color, skin color, face shape and so forth. 

Double helical structure of DNA.
(Picture from: http://dna-rna.net/)

Every single unit of DNA consisting of a phosphate group, deoxyribose sugar and nitrogen bases, called nucleotides, and DNA was polinukeotida which will form the chromosomes inside the cell nucleus. Every human being has 23 pairs of chromosomes consisting of 22 pairs of somatic chromosomes, and 1 pair of sex chromosomes (sex determining). 

The chromosomes XX male and XY female. Every person has a double spiral of DNA, a chain derived from the father, and a chain of more than mom. Thus, each child will receive a half pairs of chromosomes from the father, and half the other pairs of chromosomes from the mother. Therefore, individuals carrying both inherited trait from his father and from his mother. For DNA testing, samples can be taken from almost all parts of the body, but is generally taken from the blood (white blood cells is taken, because the red blood cells have no nucleus), inner cheek mucosa graft, nails, or hair. DNA samples can be taken from the cell nucleus and mitochondria, but the most accurate is the nucleus of the cell, because the cell nucleus can not be changed. DNA testing methods are commonly used DNA electrophoresis methods. Basically, the stages of the method of DNA testing by electrophoresis following includes several stages:

1. Sample preparation and sampling of DNA (isolation) from the body.
2. DNA purification from impurities such as proteins using techniques sentrifigasi or vacuum filtration.
3. Inclusion of purified DNA samples into the machine PCR (polymerase chain reaction) as an amplification stage.
4. The results of this amplification is the complete DNA sequence of copies of DNA samples.
5. Characterization of DNA sequences by electrophoresis coffee to see the pattern of the ribbon.
6. Stages to obtain the type of DNA typing.
7. Final stages, to match the types of DNA comparison.

A section of DNA; the sequence of the plate-like units (nucleotides) in the center carries information. (Picture from: http://commons.wikimedia.org/)

Because everyone is different DNA sequences, the number and location of DNA bands (electrophoretic patterns) individuals will also differ. PCR machine will read the DNA data and display it in the form of figures and images of DNA identification. 

DNA testing is mostly done by taking samples of somatic chromosomes, due to ties in the somatic DNA is almost the same in each individual, because it serves to form and function of organs. Sequence errors on this chromosome, can cause disruption in humans is concerned. But at the core of these cells, there is also an area known as the area of ​​STR (short tandem repeats). This area does not give the code to do something. STR is what is unique because it is different for every individual. The difference lies in the resulting base sequences and STR repeat sequence.

AGACC base sequences will be different from someone who has a sequence AGACT. Similarly, repeated sequences that are unique. STR pattern is inherited from parents. STR pattern taken from a sample of a child will be compared with STR patterns taken from his parents. If the order is the same, for example on chromosome number 3 of the child have a sequence with a repetition AGACT twice, which is the same thing was found on chromosome samples from his parents, was concluded between them have family ties. Someone said to have a close blood relationship if they have the same 16 STR pattern. DNA readings are accurate enough to prove one's relationship with the samples for comparison, so that his identity be revealed. *** [YAYI ZAKIAH | PIKIRAN RAKYAT 24052012]

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