C.8.4

=Describe the principles and used of DNA profiling=

Principle of DNA Profiling
DNA profiling (or DNA fingerprinting) is the breaking down of DNA to produce a characteristic "fingerprint" that belongs to only a certain person. The type of technique used depends on the sample and the amount of it available for analysis.

1. Extract the DNA from the blood or sample (saliva, hair, semen) of the parent 2. The DNA is cut into a specific sequence of base fragments called mini-satellites using restriction enzymes which act like molecular scissors cutting the DNA into a specific sequence of fragments. 3. DNA fragments are separated using gel electrophoresis (C.2.3). DNA is negatively charged, and will move towards the positive anode. Shorter fragments move farther and faster than longer fragments and thus your sample has been seperated according to size. The DNA is then soaked up by an ultra thin nylon sheet. 4. Stained with a fluorescent dye, or developed onto x-ray film so the pattern which is the 'fingerprint' becomes visible. 5. Compare the the DNA profiles to look for similarities and differences.
 * General steps used to obtain a DNA profile**


 * Uses of DNA Profiling**
 * to identify criminals (murderers, rapists) using DNA samples from a crime scene
 * to map evolutionary tree of extinct species
 * to determine paternity or genetic relationships between persons
 * to search for the presence of particular gene or genetic disease
 * to determine how closely related several species might be

Informative site on DNA profiling: http://www.kathyreichs.com/dnaprofiling.htm Electrophoresis gel after being stained with a fluorescent dye to reveal the unique DNA fingerprint pattern. A DNA fingerprint film showing the similarities between a mother and father and their two children.