Dna Profiling
To begin the Genetic Profiling process a forensic scientist needs a sample of an individual's DNA. This can be obtained in a number of ways, most commonly through blood tests, taking a hair from the individual or a cheek swab and from this a unique DNA profile can be compiled. This process is very young in the world of science and was only discovered in 1984 by Dr. Alec Jeffreys. Since then it's become the most widely and commonly used genetic fingerprinting system worldwide.
DNA profiling is not wholly straightforward, however, as upon first look most human DNA sequences look almost identical. This is why forensic scientists must extract the VNTR's (variable number tandem repeats) which lie on a chromosome, because they band together in a way unique to that individual. The VNTR's are shown using a number of techniques, including blotting (or 'southern' blotting as it's technically known), amplifying known variations to produce colored spots on cards and 'multiplexing' (using fluorescent dye to identify the VNTR's).
The blotting technique is not used very much today as it can take months to give results, but the PCR (Polymerase Chain Reaction) analysis technique is one which is used before almost any DNA profiling. The system involves adding an enzyme which binds to the DNA and replicates it, then heating the mixture u to 200°C before cooling it and repeating these steps 30 times until enough DNA has been formed for it to be adequately analyzed.
Genetic fingerprinting or DNA profiling is remarkably reliable, although not 100%. There are rare cases of individuals having to separate yet complete sets of DNA (these individuals are known as 'Chimeras') and their DNA can give very confounding, seemingly incorrect results.
DNA profiling is a controversial process as some DNA banks are holding the profiles of unknowing individuals. Some people argue that this is a breach of human rights and a step towards a totalitarian society, yet others argue that DNA profiling is a wholly necessary and undeniably useful process which can change the lives of individuals who don't know of their relations or their genetic make up..