|  | Public Health Safety | Medical Research

DNA Fingerprinting Methods

DNA fingerprinting, also called DNA profiling, is a technique that analyzes and compares DNA from different sources such as hair, blood, semen and other biological materials. DNA molecules are long strands tightly wound in chromosomes located in a human cell nucleus. Within the DNA cells are genes that determine characteristics of each person, allowing scientists to be able to identify specific species, sex and individual human beings. DNA fingerprinting is used in areas of science as diverse as botany and forensics.

  1. Restriction Fragment Length Polymorphism

    • Restriction fragment length polymorphism is a method of DNA fingerprinting in which DNA is extracted from a sample and cut into pieces using enzymes. This method concentrates on the bases of DNA that are repeat, which differs from other organisms. After the pieces are cut, a technique called electrophoresis separates the pieces according to length. Once sorted, the DNA fragments are labeled with radioactive material that produces a visual pattern that can be studied for minute differences. This method is very accurate, with an error probability of one in several billion. This method is a popular method for fingerprinting DNA, but it requires a considerable amount of DNA to be used.

    Short Tandem Repeat

    • The short tandem repeat is the most popular and innovative DNA fingerprinting method used for forensic cases and paternity testing. The method works by analyzing the DNA variations between individuals, called polymorphism. These individual differences are found in short sequences of DNA that lie in 13 base pair sites. The STR method analyzes how many times base pairs repeat themselves on a strand on DNA. These tests are highly accurate, with the probability of matching the exact repeat pairs at 13 sites for identical twins at one in several billion. That probability is greater for non-related individuals.

    Polymerase Chain Reaction

    • Polymerase chain reaction is a DNA fingerprinting method developed by Karry Mullis in 1983. The method was developed to establish hereditary authentication. PCR is commonly referred to as molecular photocopying because it produces multiple copies of DNA segments from a small amount of DNA, as little as 50 molecules. Once the sample has been created it can be compared with patterns from a reference sample in order to identify a possible match or connection. The major advantage to this method is that a DNA sample as small as a hair follicle or skin cell can be used to make enough copies needed for DNA fingerprinting. The drawback is that the results are not as certain as other methods.

Medical Research - Related Articles