dna analysis
Each person has a unique DNA, determined by a small fraction spread throughout the total genome. Unless you have an identical twin, no one else has the same sequence of bases in all of the sections of DNA.
DNA testing is based particularly on these unique sequences, analyzing these specific sections called markers. DNA samples can be taken from cells found in body fluids, skin, hair follicles or the inside of the cheek. After isolating the DNA from the cells, millions of copies are made using an enzyme that speeds DNA reproduction. Then, other reactions break apart the DNA molecules at specific locations in order to isolate particular markers. These markers are ultimately compared to the unknown sample. The more markers identified, the more chances that the match between two samples is accurate. DNA analysts look at a number of different markers to create a "DNA fingerprint".
All methods of collecting DNA samples, be it blood, cheek swab, skin, is equally accurate, because all cells contain the same DNA. So contrary to popular belief, a blood sample is no more accurate than a cheek swab, for example. However, when hair samples are used, the hair must be pulled, not cut, because hair is not made of living cells. If it 's pulled it carries with it some cells from the living follicle.
It is impossible to absolutely identify a person as the source of a DNA sample without looking at the whole of that person 's DNA. With identical twins, it 's never possible, but with many markers the chances for an accurate identification are favorable. Typically, the comparison is made using between 2 and 13 markers. With 13 or close, it 's extremely unlikely that an incorrect identification will occur, however it is not absolutely impossible.
Still, if an absolute match is hardly possible, a mismatch is very easy to identify through DNA analysis. For example, in a criminal investigation a suspect can be easily eliminated as the source of a sample based on the absence of a single marker. All DNA from a particular person must match from one end of each molecule to the other.
DNA testing has consisted a huge breakthrough, and is a strong pillar in any criminal investigation. DNA analysis has even been used to reopen old cases that were considered solved, because DNA samples remain useful for a very long time. The results are far more accurate and reliable than any other form of identification, and numerous people have been cleared for crimes they did not commit based on DNA analysis.
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By:Alexandra Cazacu
Article Source: dna analysis
