Laboratory Exercise #8
DNA Fingerprinting: Identification of DNA Restriction Fragmentation Patterns

I. Introduction
All humans have in common the coding sequences of their DNA, but, unless you are an identical twin, the non-coding sequences of your DNA are like no other person’s on the planet. The bulk of human DNA does not code for specific genes and is highly repetitive. A British geneticist, Alec Jefferies, developed laboratory techniques in 1984 that became known as DNA fingerprinting. These techniques can identify the differences in repetitive nucleotide sequences between individuals, but also show where sequences are the same and, therefore, have been inherited. DNA fingerprinting can be used to detect genetic disorders, identify individuals, settle paternity disputes and determine guilt or innocence when presented as evidence in a crime scene investigation. This ability to identify an individual is enhanced by the variety of substances that contain DNA, including blood, semen, saliva, hair, urine, bone, teeth, feces, and tissues.
DNA profiling is one of the most important applications of the techniques used in the field of forensics. Crime scene investigation routinely includes the collection of evidence that may contain DNA in the hopes that it may provide a link to a suspect. The genetic comparison doesn't require that investigators look at the entire genome of the DNA samples found at the crime scene or from a suspect. Instead, forensic scientists use genetic markers, sequences of the DNA located within the non-coding regions that are known to vary from person to person. Because these markers are inherited, they are more likely to match between related individuals than in nonrelatives. They then check for the presence or absence of those sequences in a sample taken from a suspect. Once forensic investigators have genetic profiles in place, they