Biology Reference
In-Depth Information
Event
Transfer of material
Identification/Collection of material
Characterization of material
DNA extraction
Quantification of DNA
PCR amplification
Detection of PCR products
(DNA Profile)
Analysis and interpretation of profile
Statistical evaluation of DNA profile
Report
Figure 1.2
Processes involved in generating a DNA profile following a crime. Some types of
material, in particular blood and semen, are often characterized before DNA is extracted, allowing
the DNA evidence to be linked to a cell type and possible transfer mechanism
Southern blotting [70] and in 1980 the analysis of the first highly polymorphic locus
was reported, where the polymorphism was caused by differences in the lengths of
the alleles [71].
It was not until September 1984 that Alec Jeffreys realized the potential forensic
application of the minisatellite loci [1, 72, 73]. The technique developed by Jeffreys
entailed extracting DNA and cutting it with a restriction enzyme before carrying out
agarose gel electrophoresis, Southern blotting and probe hybridization to detect the
polymorphic loci. The end result was a series of black bands on X-ray film, which
was called a DNA fingerprint (Figure 1.3).
