The DNA of every individual is different unless you
are an identical twin. DNA technology has therefore
become one of the most important tools for identifying
individuals in both criminal cases and paternity disputes
What is DNA Fingerprinting?
The use of the the small stretches of DNA that vary among individuals to determine the probability of a match between samples from different people.
DNA fingerprinting is routinely used to identify potential suspects using DNA left behind at a crime scene. Police have created DNA Fingerprints from samples as diverse as chewing gum, cigarette butts, toenail clippings and even watch straps! DNA fingerprinting has also been used to help us …
… cook basmati rice to perfection
… monitor illegal trade in protected species
… confirm the authenticity of wine
Stages in generating a DNA profile
1) DNA isolation
2) Restriction enzyme digestion
3) Gel electrophoresis
4) Blotting DNA onto afilter
5) Hybridisation with a nucleic
A sample from the subject is matched with a referenced sample (DNA sample from crime scene or a relative in a civil case)
Limited samples of DNA are amplified using PCR
DNA profiling relies on repetitive, hypervariable DNA
FORENSICS : An example
A terrible crime has taken place. A middle-aged man was murdered during a burglary. Forensic scientists collected a blood sample from the victim and a sample from the scene of the crime. Blood samples were also taken from four suspects identified by the police. Forensic scientists have prepared the autoradiograph on next slide from DNA extracted from the blood samples. The prosecution wishes to use it as evidence in a court case
Which part of a blood sample is required for this analysis?
Who should be charged with the crime?
The prosecution wishes to use the forensic evidence in court but is concerned that the autoradiograph is not conclusive proof. Why?
How could the accuracy of the analysis be improved?