DNA´s lasting imprint

The use of DNA typing for the examination of forensic casework and the establishment of paternity is discussed. A description is given of DNA-based identification testing procedures, most of which involve the use of restriction endonucleases, DNA probes, and Southern blot hybridization. Restriction endonucleases are enzymes that cleave a person´s DNA, at specific recognition sites, into a reproducible pattern of fragments. DNA probes are relatively small pieces of DNA (also known as oligonucleotides), which are selected because they recognize specific genetic sequences of interest on a segment of target DNA. The probe and detected sequence (known as a complementary sequence) fit together specifically like the two halves of a zipper. Southern blot hybridization is essentially the process by which specific target DNA fragments of interest are isolated, detected, and visualized. The differences between testing for a crime scene investigation and testing the paternity establishment are considered. The impact of DNA testing is discussed.<>