DNA profiling compares variable numbers of tandem repeats (VNTRs) in DNA samples from crime scenes and suspects. If the VNTRs match, then the suspect's DNA was at the crime scene. DNA profiling can also determine paternity by testing mitochondrial DNA passed maternally or Y-chromosomes passed paternally. While very accurate, DNA profiling has social implications like falsely convicted persons being freed or family issues when true paternity is discovered.

1. DNA Profiling and Use in Forensic Investigations and Paternity Tests by J.C. Hall and Eli Rosenthal

2. What are DNA profiles? In 1985, the English geneticist Alec Jeffrey discovered that certain regions of DNA contained DNA sequences that were constantly repeated contiguously. He also discovered that the lengths of these sections differed from person to person, and developed a method to test for the differences in length. By comparing these sections, he developed a human identity test, known as the DNA profile. Professor Sir Alec Jeffreys

3. How does DNA profiling work? DNA profiling compares the sections of DNA repeated, called variable numbers of tandem repeats, or VNTRs, of the samples from the crime scene, and compares them to samples taken from suspects. Because every person has an individual set of VNTRs, if the compiled set of VNTRs of the DNA at the crime scene matches with that of a suspect, then that person’s DNA was definitely at the crime scene. In the photo at left, the DNA profile taken from a bloodstain at the crime scene matches the DNA profile of the suspect third from the left.

4. DNA Profiling in the Field Currently, DNA profiling is only done in the lab, at a rate of up to three samples per hour, due to the process used to create the profile. However, some Australian forensics laboratories have developed or purchased analysing equipment that simultaneously runs analysis of different VNTRs, greatly improving the processing rate. Also, the U.S. Department of Justice is funding a number of research projects designed to create a DNA analyser on microchip, which would allow for quick, on-the-spot creation and storage of DNA profiles.

5. DNA Profiling as a Paternity Test Besides as a useful tool in forensic investigation, DNA profiling can be used to determine a person’s lineage. Different companies, such as Family Tree DNA, use DNA profiling to determine either paternal or maternal lineage. Maternal lineage is determined through testing for mitochondrial DNA, or mtDNA, which is passed down only through the mother. Paternal lineage is determined most often through a Y-STR test, which tests for very specific repeats (STRs) on the Y-chromosome, which is only passed down from males. A perfect match indicates a very close male ancestor.

6. Social Implications There are a variety of social implications that stem from the use of DNA profiling. These include relief for wrongly convicted persons who are freed, problems within a family when the father learns he is not the father of his child, and self-esteem issues for a child who learns of his true father. In addition, there are organisations such as the UK-based Liberty that believe keeping DNA profiles on file is a violation of the right to a private life.

7. TOK Aspects While DNA profiling is a very accurate form of identifying paternity, testing for blood groups is a simple manner to test for absence of relationships between two people. This can be considered as a less personal or less intrusive but less accurate form of determination. In addition, the importance of DNA profiling as a forensics tool can be assessed by discussing several recent high-profile legal cases, such as that of O.J. Simpson or of Kirk Bloodsworth.

8. Aim 7 - Bioinformatics Bioinformatics is the process of applying statistics and computer science to molecular biology, and is intended to increase scientists’ knowledge of biological processes. The most common activities in bioinformatics are mapping, analysing, and comparing DNA and protein sequences, and creating three-dimensional renderings of the sequences. In keeping with its purpose of applying computationally-intence methods to statistics, bioinformaticists have developed online simulations that can be used for anything from automatically generating the products of RNA translation for an input set to calculating the amino acid composition and molecular weight of a given protein sequence. The human X chromosome, mapped by the HGP.

12. Evolutionary Relationships Analysis of various polymorphic loci in worldwide populations has given rise to analysis of the genetic relationships between different nationalities. They are also helping to answer the question of whether humans originated from 1 source or from multiple, a 2007 study concluded that all humans came out of Africa through an index of skull measurements and genetic databases.