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Interactives -- DNA

Implications & Ethics : Studying Our Genetic History

The genome has information about human evolution and human migrations. By studying mitochondrial DNA--DNA found not in the nucleus of cells but inside structures called mitochondria--researchers can study the migration of females throughout the world over long stretches of time. This is because mitochondria, the cells' power plants, are passed only from mother to child. Studying the Y chromosome, on the other hand, is helpful for tracing the migration of males. We can also compare the human genome to the genomes of other organisms to see how closely related we are to them.

DNA Forensics

Genetic analysis has become increasingly important for identifying individuals. To do genetic typing requires only a small amount of DNA, extracted from blood, saliva, hair follicles, or other tissue. Forensic scientists probe 13 specific DNA regions, or markers, that are highly variable among individuals. The profile of this set of 13 markers creates a genetic "fingerprint" of the person. While related individuals may share some markers, the odds that any two people will have the same 13 markers are astronomically high. A person's genetic fingerprint is therefore as distinctive as a regular fingerprint.

Forensic scientists have used genetic typing to identify-and to exonerate-criminal suspects, to identify crime victims, establish paternity and other familial relationships, detect and identify pathogenic bacteria and pollutants, match organ donors with recipients, and more.

To aid in forensic investigations, the FBI maintains the Combined DNA Index System, or CODIS. This national database contains more than a million DNA profiles of convicted criminals and tens of thousands of profiles, not yet linked to a particular individual, that have been developed from crime scene evidence.


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