Download DNA Fingerprinting and Forensic Analysis - ASAB-NUST

LECTURE 22:
Forensic Sciences and DNA
Fingerprinting
Biotechnology; 3 Credit hours
Atta-ur-Rahman School of Applied Biosciences (ASAB)
National University of Sciences and Technology (NUST)
Forensic Science
• Forensic biology is the application of biology
to law enforcement
• The analysis of the biological or genetic
properties of evidence for identification
• It is used to establish identity in criminal
investigation, in case of disputed paternity, or
in historical or archaeological research
The Genetic Basis of Identity
1.
2.
3.
4.
Fingerprints
Retinal Scan
Blood Typing
DNA Fingerprinting
1- Fingerprints
• Finger prints are the classic example of a
phenotype used in law enforcement
• They are due to the variation in the pattern of
dermal ridges, small skin elevation on your
fingers
Fingerprints
• Fingerprints pattern depends on more than one
gene
• They are multigenic
• This create huge genetic diversity underlying this
phenotype
• One could expect fingerprints of twins identical,
but they are not
• Minor variation happens because of
environmental factors
• This science is being used for identification by
late 1800
2- Retinal Scan
• Retinal scan provide a more high tech form of
unique identification
• It take advantage of unique pattern of blood
vessels on the retina on the back side of eye
Retinal Scan
• Scanning typically take about a minute
• Several scans are required
• Infrared light is used for this job, because
blood vessel on the retina absorb this better
than the surrounding tissue
• A computer algorithm is used to convert this
scan into digital data
• There are about 10 fold more information on
retinal scan than in fingerprints
Applications
• Application in high security system
• CIA, FBI, NASA and prison system
• Now it is being employed on animal
identification
• Fingerprinting in many security system and
also in law enforcement system (crime secene)
3- Blood Typing
• Blood typing has been used in the courtroom
for more than 50 years
• Other body fluids i.e. Sweat, tears, urine,
saliva and semen also have cells with surface
proteins that can be analyzed
• RBC contain many proteins and lipids for the
identification
Blood Typing
• Galactose transferase
• N-acetylgalactosamine
transferase
Blood Typing
Inheritance of ABO blood system
4- What is a DNA fingerprint?
• DNA profiling (also called DNA testing, DNA
typing, or genetic fingerprinting) is a technique
employed by forensic scientists to assist in the
identification of individuals by their respective
DNA profiles.
• DNA profiles are code sets of numbers that
reflect a person's DNA makeup, which can also be
used as the person's identifier.
• It is used for parental testing and crime
investigation.
DNA fingerprint Profiling Analysis
a)
b)
c)
d)
e)
f)
RFLP Analysis
PCR Analysis
STR Analysis
AmpFLP Analysis
Mitochondrial DNA Analysis
Y-chromosome DNA Analysis
a. RFLP Analysis
b. PCR Analysis
c. STR Analysis
PCR Analysis
Paternity Testing
PCR amplification,
then DNA fingerprinting
Mother’s STRs
Offspring STRs
STRs of suspected Father
-
Is the suspect the father?
d. Genealogies by Mitochondrial & Ychromosome DNA Analysis
• Genealogy is the study of
families and the tracing
of their lineages and
history
• Mitochondrial DNA is
maternally inherited and
often used to specifically
trace maternal ancestry
• Y chromosome can be
used to trace male
ancestry
Genealogies by Mitochondrial & Ychromosome DNA Analysis
• It is possible to submit
personal samples of
DNA for analysis to
companies such as
Oxford ancestor
• Their matri-Line service
allows persons of
European decedent to
trace their maternal
ancestry back to one of
seven ancestral females
Genealogies by Mitochondrial & Ychromosome DNA Analysis
• Y-chromosome follows a paternal pattern of
inheritance.
• The Y-chromosome contain many STR
sequence in non-coding region.
• Y linked STR loci are specific to Y-chromosome
• They find useful application in forensic
analysis in case of sexual assault.