McDougal Littell - Biology

DNA "Fingerprinting"

Who committed the crime? Who’s this unidentified victim? Whose lost child is this? It used to be that the best way to answer questions like this was based on the odd fact that the skin on the ends of our fingers and toes have unique patterns of whorls and lines - "fingerprints" - that can be used to tell one individual from another. But even the most experienced fingerprint expert uses subjective judgment to find a match and requires a clear imprint to do so, something only available in a limited number of cases. The advent of convenient and rapid methods for extracting, cutting, copying and sequencing DNA, however, has completely changed our ability to not only identify individuals based on the unique DNA sequences we each possess, but also to tell who is related to whom. Even tiny samples of blood, hair, salvia or other tissues from a body can contain enough DNA to match individuals to those samples with extreme reliability, or to say that an individual does not match the sample (a point that has led to the exoneration of many people previously convicted on less reliable evidence). DNA analysis is now commonly used to determine the parentage of children, to match organ donors, to study the population biology of animals and plants, and to trace the origins and dispersal of human societies across prehistoric times.