DNA FINGERPRINTING AND FORENSIC APPLICATIONS
May 11, 2015
DNA FINGERPRINTING AND FORENSIC APPLICATIONS
DNA(DEOXYRIBONUCLEIC ACID)
DNA is a chemical structure that forms the genes.
DNA is a double helix, two strands of genetic material spiraled around each other.
Adenine, Guanine, Thymine ,Cytosine
WHAT IS DNA FINGERPRINTING ?
The chemical structure of everyone DNA is same but the difference lies in the base pairs
Using base pairs everyone can be solely identified but it is time consuming as there are millions of base pairs
Instead, scientists are able to use a shorter method, because of repeating patterns in DNA
They are able to determine whether two DNA samples are from the same person, related people, or non-related people.
PROCESS OF DNA FINGERPRINTING
It involves six steps1. The process begins with the cell or sample
from which the DNA is extracted.2. The DNA is cut into fragments using
restriction enzymes , The fragments are then separated into bands by electrophoresis through agarose gel .
3. The DNA band pattern is transferred into a nylon membrane .
ELECTROPHORESIS
CONT….
4. A radioactive DNA probe is introduced .The DNA probe binds to specific DNA sequences of the nylon membrane
5. The excess probe material is washed away leaving the unique DNA pattern
6. The radioactive DNA pattern is transferred to X-ray film by direct exposure .When developed the resultant visible pattern is DNA fingerprint.
DNA FINGERPRINTING PROCEDURESDAY ONE
DNA FINGERPRINTING PROCEDURESDAY TWO
DNA FINGERPRINTING PROCEDURESDAY THREE
Applications 1. Paternity and also
the Maternity .2. Criminal
identification and Forensics .
3. Personal identification.
Problems1. Generating a high
probability .2. Technical difficulties
FORENSIC DNA
DNA Sequences are compared to each other.
AGCTAGATCGTTATTCCGAG
AGCTAGATCGTTATTCCGAG
Hair found onSuspect
Victim
Conclusion: Hair may have come from the victim.
FORENSIC DNA (MITOCHONDRIA)
DNA Sequences are compared to each other.
AGCTAGATTGTTATTCCGAG
AGCTAGATCGTTATTCCGAG
Hair found onSuspect
Victim
Conclusion: Hair did not come from the victim
FORENSIC DNA
AGCTAGATTGTTATTCCGAG
AGCTAGATCGTTATTCCGAG
Blood butt at crime scene
Suspect #1
Conclusion: Blood could be from Suspects #2, #4 or other person with the same sequence.
AGCTAGATTGTTATTCCGAGSuspect #2
AGCTTGATTGTTATTCCGAGSuspect #3
AGCTAGATTGTTATTCCGAGSuspect #4
LET’S COMPARE…….bloodstain Satheesh Dheva John Ramalingam
DO WE HAVE A MATCH?bloodstain Satheesh Dheva John Ramalingam