BRAINCAKEForensic Science
Forensic scientists use DNA profiling to link people to crime scenes, to rule suspects out and to identify bodies.
Collecting and comparing samples
Cells containing DNA are left behind as blood, semen, saliva, hair roots or skin cells. Only a tiny amount is needed because PCR can amplify it. A DNA profile is produced from the crime scene sample and compared with profiles from suspects, which are usually taken from cheek cells using a mouth swab.
If the bands of the crime scene profile and a suspect's profile are in exactly the same positions at every locus, the profiles match. This is strong evidence that the DNA came from that person. If even one band is different, the suspect can be excluded: the DNA did not come from them.
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Key terms in this lesson
- dna profiling
- Producing and comparing a pattern of DNA fragment lengths, typically at several STR loci, that is unique or nearly unique to an individual.
More in Gene Sequencing
- DNA Sequencing
- Using DNA Sequencing
- Using DNA Sequencing to Manage Disease
- Introns and Satellite DNA
- DNA Profiles
- Gel Electrophoresis
- Southern Blotting and Gene Probes
- Paternity Testing
All 12 lessons in Gene Sequencing · All Edexcel A-level Biology topics