Introduction
"British geneticist Alec Jeffreys began working in 1977 on a technique that could identify individuals through samples of their DNA. In 1984, he and colleagues devised a way to use a newly discovered property of DNA, isolated areas of great variability between individuals called restriction fragment length polymorphisms (RFLP), for forensic identification—the original DNA fingerprint.
In 1986, police asked Jeffreys for help in finding a man who had raped and killed two girls. DNA tests exonerated the primary suspect. Through a genetic dragnet, police found the perpetrator, Colin Pitchfork, who gave himself away when he asked a friend for a substitute blood sample.
Within a year, genetic fingerprinting was making the unique molecular structures of victims and suspects visible in criminal investigations around the world. Today, RFLP-based DNA analysis is being supplanted by newer techniques of genetic identification." Source: "Cases: Alec Jeffreys and the Pitchfork murder case: the origins of DNA profiling", Visible Proofs: Forensic Views of the Body. Courtesy of the U.S. National Library of Medicine.
In this lesson and the ones that follow in this unit, you will learn about the structure of DNA and how it is used by forensic scientists today.
Following successful completion of this lesson, students will be able to...
- Describe the basic structure and function of DNA.
- Review a historical case and describe how DNA was utilized.
Essential Questions
- What is DNA and how is it unique to each individual?
- What are the different types of DNA and in what type of cases is each more reliable?
Enduring Understandings
- Forensics requires a team of practitioners representing all areas of science.
- DNA can be retrieved from a variety of human cells and utilized to directly link an individual to a crime scene with reasonable certainty.
The above objectives correspond with the Alabama Course of Study: Forensic Science and Crime Scene Investigation standards: 1, 19.