DNA Fingerprinting process

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DNA Fingerprinting in other words DNA profiling is a technique that uses only samples of individual’s DNA to differentiate them from others. Based on the fact that every individual‘s DNA profile is unique, the process of DNA fingerprinting is done to acquire the specific DNA profile of the individual. DNA Fingerprinting could be applied to Forensic Science to solve crime, Genetic Screening to identify genetic disorders or hereditary screening to identify individuals that are genetically related.


Once the DNA is collected from the individual and extracted from the cell, with breaking the cell membrane and the nuclear membrane by using detergent, the DNA is photocopied using the Polymerase Chain Reaction Technique. The specific sequence of the DNA molecule that is to be replicated must be identified beforehand. A pair of primers – DNA sequences that are 18-25 base pairs long and are specifically complementary to the DNA sequence  identified- are required to be put together in order to mark the chunk of DNA that is to be copied.

Why is PCR done?

It is done to allow a very large number of human insulin genes available to work with; because when the recombinant plasmids (at the end of the process) containing the insulin gene are being reinserted into the E.coli cells, there is a very low possibility that all the plasmids will be able to make it to the desired location (E.coli cells).

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How is PCR Done?

PCR is a 3 stage cycle;

  1. The first stage is the Denaturing of DNA which is carried out at 94-96°C. At this stage, the high temperature breaks up the hydrogen bonds which hold the double stranded DNA together and the strands separate into two single strands.
  2. The second stage includes the primers finding the complementary sequences in the DNA and combine with them at a temperature between 50-65°C. It is called the annealing of primers.
  3. At 72°C, the unattached DNA nucleotides bond (Taq polymerase allows the bonding to take place and ...

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