DNA Profiling

DNA profiling/fingerprinting is a method used to identify an individual from a sample of DNA by looking at unique patterns in their DNA.

DNA fingerprinting was invented in 1984 by Professor Sir Alec Jeffreys after he realised you could detect variations in human DNA, in the form of these minisatellites. DNA fingerprinting is a technique that simultaneously detects lots of minisatellites in the genome to produce a pattern unique to an individual. This is a DNA fingerprint. The probability of having two people with the same DNA fingerprint that are not identical twins is very small. Just like your actual fingerprint, your DNA fingerprint is something you are born with, it is unique to you.

DNA profiling

Alec Jeffreys, the pioneer of DNA profiling.

dna profiling

Illustration showing the steps in DNA fingerprinting. [Image credit: Genome Research Limited]

dna profiling

Illustration showing the steps in DNA profiling. [Image credit: Genome Research Limited]

What is a DNA profile? :

One way to produce a DNA profile, is for scientists to examine STRs at 10 or more genetic loci. These genetic loci are usually on different chromosomes. A DNA profile can tell the scientist if the DNA is from a man or woman, and if the sample being tested belongs to a particular person.

DNA profiling is used to :

• Identify the probable origin of a body fluid sample associated with a crime or crime scene.
• Reveal family relationships
• Identify disaster victims, for example, ESR scientists travelled to Thailand to help identify victims of the 2004 Boxing Day tsunami.
DNA Fingerprint Test :

To get your DNA fingerprint, you would give a sample of cells from your body. This can come from a swab inside your mouth, from your skin, the roots of your hair, or your saliva, sweat, or other body fluids. Blood is usually the easiest way. Lab workers treat the sample with chemicals to separate the DNA, which is then dissolved in water. Your DNA is cut into smaller segments with another chemical process to get sections of 5 to10 base pairs that repeat themselves. Technicians copy those tiny sections millions of times to make the samples longer for easier study. Lab workers take those strips of DNA and mix them into a gel. Then they run an electric current through the gel, which separates smaller strands of DNA from the larger ones. A dye added to the gel makes the DNA strips stand out when they’re placed against an ultraviolet light or lit up with a laser. The more these short segments are tested, the more accurate the DNA profile will be. The strips will show a barcode-like pattern that can then be compared to the results from another sample of DNA to find a match.
How much does DNA profiling cost? :
Prices range from £100 to £200 for a basic DNA profile, but it’s worth mentioning that the cost largely depends on what you intend to do with it. One of the major factors that you need to consider, and which significantly impacts the cost, is whether you want your DNA profile to be legally admissible or not. Legal DNA profiles cost more than peace of mind versions, but if there’s a chance that your profile will be used in legal proceedings, it’s worth paying extra for.

Interesting Facts about DNA fingerprinting :

• DNA fingerprinting doesn’t have much to do with actual fingerprints, but it refers to the fingerprint of someone’s DNA, which is unique to themself.
• It was made famous when prosecuters used it to acuse O.J. Simpson to a double murder.
• Some people, called chimeras, have different DNA in different cells.
• DNA fingerprinting can be used in paternity testing to find out who the father of a child is. Without this, fathers could leave their children, and not have to pay fees.
• Only one sample is needed for a person’s DNA, unless they are chimeras.
• It is possible for the DNA to become contaminated.
• The chances of a mismatch happening was improved from one in fifty million to one in a billion.

dna profiling

-Shreesha Balan

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