1. Identification Papers People usually carry something that carries their name e.g. Driving Licence Bank Cards Diary Phone Sometimes their clothes are named
2. Fingerprints The skin on the fingers, palms and soles of the feet is ridged Sweat and sectretions from the sebaceous glands (in skin) cover the fingers with an oil
When we touch things the oil is left behind giving an impression of the pattern of folds on our skin Use of aluminium powder or Magnetic powder or Ninhydrin spray (shows amino acids in sweat as purple) Reveals a fingerprint
3. Dental Records Used if a body is badly decomposed, damaged or burned Can be as reliable as fingerprints What can we tell about this person from their x-ray?
4. Genetic Fingerprinting Works on the premise that everyone’s DNA is unique Sample of genetic material is cut into sections using a restriction enzyme Pieces of DNA are run through an electrophoresis gel
What does the genetic fingerprint look for? Repeated sections of DNA within introns
The repeated sections are called satellites They can be small (2 to 4 bases) = Micro-Satellite Or large (20 to 50 bases) = Mini-Satellite Satellites can be repeated anything from 5 to 500 times The exact number of repeats is very different from person to person. This allows a method for identifying them! A “ genetic fingerprint ”
The pattern of DNA produced by an electrophoresis gel is the “genetic fingerprint” This depends on the number of repeats of different satellites in DNA, which is unique for different people! A Genetic Fingerprint