Since September 11, 2001, the world has learned to appreciate the availability of forensic tests. Such forensic tests helped with the identification of various body parts found at “ground zero,” the former location of the World Trade Center. Family members eagerly searched for hair samples, in order to help with confirmation of the test results. The testers would analyze the DNA of a hair sample from a deceased relative and then examine the test results for a body part found at “ground zero.” If they were the same, then the relative had at least a little something to bury in the ground.
The basic methodology used in forensic tests came out of experiments conducted by Walter Gilbert and Fred Sanger. Acting independently in 1975, the two researchers developed two different techniques. Both techniques could be used to achieve DNA sequencing. Reports about both techniques ushered in the era of new forensic tests, tests that sought to identity a murderer by looking at the DNA from objects at a crime scene.
Yet the DNA sequencing methods introduced by Gilbert and Sanger would not have been possible without the findings of Warner Arber, Hamilton Smith and Daniel Nathans. They discovered restriction enzymes. Restriction enzymes are an important part of forensic tests, because those enzymes can cut DNA into small pieces with known ends. Because those pieces have known ends, they also have a known size. Sanger and Gilbert used available knowledge about the size of those pieces in designing their DNA sequencing techniques.
The knowledge available to Sanger and Gilbert told them that each of the different DNA pieces had a different weight. They used that knowledge to sort the pieces by their weight. That sorting took place in an electric field. The pieces traveled through the field much like a balloon floating in the atmosphere. For example, if such a balloon is heavier than the atmospheric air, then the balloon sinks; if the balloon is lighter than the atmospheric air, then the balloon rises.
Every person will produce a unique set of DNA fragments when their DNA becomes exposed to restriction enzymes. The exploitation of that fact forms the basis of forensic tests. Those tests look at the pattern of the DNA pieces in the electric field. Such forensic tests became the focus of much media attention in the mid- 1990’s.
At that time Los Angeles County was the scene of the closely-watched O.J. Simpson trial. During that trial, the jury heard a great deal about evidence obtained from forensic tests. The prosecution tried to use the information from the tests to convince the jury that Simpson’s DNA had been found at the scene of the crime. The trial did not reveal any problems with the forensic tests, but it did show the need for care when collecting the samples to use in such tests.
The conclusion of that trail did not bring an end to mention of forensic tests on TV. In fact, such tests are now mentioned almost weekly in some TV programs. Programs such as “Cold Case” and “CSI” have characters that rely on forensic tests to help with the solving of a crime. The tests reveal the DNA of the murderer or other criminal. In those fictionalized stories, unlike the true story of the O.J. Simpson trial, the gathering of the evidence seems to present no problems.
The basic methodology used in forensic tests came out of experiments conducted by Walter Gilbert and Fred Sanger. Acting independently in 1975, the two researchers developed two different techniques. Both techniques could be used to achieve DNA sequencing. Reports about both techniques ushered in the era of new forensic tests, tests that sought to identity a murderer by looking at the DNA from objects at a crime scene.
Yet the DNA sequencing methods introduced by Gilbert and Sanger would not have been possible without the findings of Warner Arber, Hamilton Smith and Daniel Nathans. They discovered restriction enzymes. Restriction enzymes are an important part of forensic tests, because those enzymes can cut DNA into small pieces with known ends. Because those pieces have known ends, they also have a known size. Sanger and Gilbert used available knowledge about the size of those pieces in designing their DNA sequencing techniques.
The knowledge available to Sanger and Gilbert told them that each of the different DNA pieces had a different weight. They used that knowledge to sort the pieces by their weight. That sorting took place in an electric field. The pieces traveled through the field much like a balloon floating in the atmosphere. For example, if such a balloon is heavier than the atmospheric air, then the balloon sinks; if the balloon is lighter than the atmospheric air, then the balloon rises.
Every person will produce a unique set of DNA fragments when their DNA becomes exposed to restriction enzymes. The exploitation of that fact forms the basis of forensic tests. Those tests look at the pattern of the DNA pieces in the electric field. Such forensic tests became the focus of much media attention in the mid- 1990’s.
At that time Los Angeles County was the scene of the closely-watched O.J. Simpson trial. During that trial, the jury heard a great deal about evidence obtained from forensic tests. The prosecution tried to use the information from the tests to convince the jury that Simpson’s DNA had been found at the scene of the crime. The trial did not reveal any problems with the forensic tests, but it did show the need for care when collecting the samples to use in such tests.
The conclusion of that trail did not bring an end to mention of forensic tests on TV. In fact, such tests are now mentioned almost weekly in some TV programs. Programs such as “Cold Case” and “CSI” have characters that rely on forensic tests to help with the solving of a crime. The tests reveal the DNA of the murderer or other criminal. In those fictionalized stories, unlike the true story of the O.J. Simpson trial, the gathering of the evidence seems to present no problems.
