DNA (Deoxiribo Nucleic Acid) is present in virtually all cells that living organisms are made of. Human DNA is in the form of various strands trapped in the nucleus of the cell. These strands of DNA are called chromosomes. The chromosomes come in pairs, one half is inherited from the mother and the other half from the father. In total, 23 human chromosomes which can be divided into 22 autosomal chromosomes and one pair of sex chromosomes. The sex chromosomes in males are present as XY and XX in females.

The hyper variable regions of chromosomes are present, there are large numbers of repetitive DNA elements that Short Tandem Repeats (STR’s) are mentioned. At certain locations, which locus or loci are known in the plural, between individuals differ in the number and hence the length of this repetitive DNA elements. 

The variation in the numbers of forms are repetitive pieces of DNA called alleles or characteristics. These DNA markers are the foundation of forensic DNA profiling. 

By the variation in DNA markers in the different loci can distinguish between persons. The different DNA characteristics in the study are visible as peaks, can be displayed with one digit. The set of numbers obtained from the DNA test to various samples can be compared.

DNA research methods

DNA-isolation: Where documentary evidence samples taken for DNA testing, the goal here, as pure as possible to obtain DNA. In the isolation of DNA is therefore sought possible contaminants and cellular material that is not related to DNA testing to remove. This will eventually clear liquid containing the DNA to investigate. This liquid is called the DNA isolate.

PCR: In the study we used a method which, following the DNA isolation, to determine the DNA fragments are increased. This is done using the polymerase chain reaction (PCR). These are using the enzyme DNA polymerase to the DNA fragments gradually increased. In general, using 28 steps of this increase to a large number of copies of DNA fragments to obtain. Eventually, in this step the so-called PCR product was obtained.

DNA-analysis: The length of the increased DNA fragments is determined by capillary electrophoresis. During the propagation steps of the DNA fragments different color labels attached. The length of the DNA fragments can then be accurately determined by the PCR products into an electric field to separate after detection with a CCD camera can take place.