2. OVERVIEW
• Introduction
• Historical Background
• Types of DNA profiling
• Procedure
• Applications

3. The most powerful and
awesome tool acquired
by humans since the
splitting of atoms”
The Time
Magazine (U.S.A)
“

4. INTRODUCTION
• DNA profiling (also
called DNA testing, DNA
typing, or genetic
fingerprinting) is “technology
of using tandem repeats of
individuals to identify
individuals”

5. Although the majority of our DNA
is the same, there are short
pieces called “microsatellites”, which repeats many
times in a person’s DNA. It’s the
pattern of repeats that are
different between individuals.
Knowing these microsatellite DNA sequences is
the basis of “DNA

6. WHO INVENTED
DNA
fingerprinting

7. university of
Leicester, UK in
1985.
In 1994,he was
knighted by Queen
Elizabeth for
services to Science
and technology.

8. KEY
CONCEPT
DNA profiling r finger printing
identifies people at molecular
level.

9. can by used for identification.
• Based on non coding regions
of DNA
•Non coding regions have
repeating DNA sequences
•Number of repeats differs
between people
•Banding pattern on a gel is a
DNA fingerprint

10. TYPES OF DNA
FINGERPRINTING

11. RFLP-based (Restriction
fragments length polymorphism)
•Original method developed by Alec
Jeffreys
DNA can be extracted from of DNA
•1st step is the Extraction
almost any human tissue.
Sources of DNA found at a
crime scene might include
blood, semen, tissue from a
deceased victim, cells in a
hair follicle, and even saliva.
DNA extracted from items of
evidence is compared to DNA

12. DNA EXTRACTION
METHOD
To extract DNA
, most
commonly
used detergent
is Sodium
Dodecyl Sulfate

13. Digestion of proteins and
lipids around the cell and it
nucleus

14. DNA is extracted from
sample
•DNA in the
nucleus of the
cell is
molded, folded, a
nd protected by
Proteins
•Proteinase K is

15. Ethanol
Precipitation
The DNA must be purified from the cell
extract.
Ethanol lowers the effective water
concentration, causing large biomolecules to interpenetrate and
aggregate. The result is a visible
precipitate at the interface, where the
ethanol is concentrated.
 DNA will rise into the alcohol layer from

16. Step 2.DNA cuts with the
help of Restriction
Endonuclease
DNA is cut into millions of small
fragments with the help of restriction
Endonuclease
Restriction enzymes chop DNA at
specific sequences.
the patterns occur in different places in

18. We are ALL a little bit different!
BIG
WAQAS’ DNA
LITTL
E
AHMED NAWAZ’
DNA

19. Our DNA has different sizes of pieces so
it makes a different pattern when it’s all
WAQAS
cut up ’ DNA
AHMED NAWAZ’ DNA

20. RFLP Analysis
Everyone has
genetic
sequences called
variable number
tandem repeats, or
VNTRs
– Everyone has
different
amounts of VNTRs

21. GEL
ELECTROPHORESIS
Fragments of DNA from restriction
enzyme cleavage
are separated from each other when they
migrate
through a support called an agarose gel
– It is similar to the yummy food Jell-O
gelatin
– It is actually made out of some of the
same ingredients
• The size-based separation of Molecules

23. GEL
ELECTROPHORESIS
The separated DNA fragments are then
drawn out of
the gel using a nylon membrane
• The nylon membrane is treated with
chemicals that
break the hydrogen bonds in DNA and
separate the
strands
• The single stranded DNA is cross linked
to the nylon
membrane

24. DNA having
repeat
sequences will
only be bound
to the
radioactive or
fluorescent
probe.

25. The final step to making a genetic
fingerprint is to place a photographic
film on top of the nylon surface. The
probes leave marks on the film
wherever they attached to the
RFLPs. Dark bands will then show up
when the film is developed, which
marks the length of the RFLPs that
were hybridized. Researchers are
then able to read the fingerprint and
match it to others. They do this by

27. DNA fingerprints can b used to
determine which bone fragment
belongs to which individual.

28. STRs & PCR
Currently, the most popular method of DNA fingerprinting
are short tandem
repeats, or STRs for short
Unlike VNTRs which analyze minisatellites that have
repeat
sequences of 9-80 base pairs, STRs use microsatellites
which have repeat sequences of
only 2-5 base pairs, introducing the “less is more”
This was a big step forward in
philosophy to the world of DNAforensic science since the
length of DNA
fingerprinting.
fragment being analyzed is short enough to be amplified
by polymerase chain reaction
(PCR), so now we are able to analyze a very small

29. PCR was developed in the mid 1980’s
and used the same principles that cells
use to replicate DNA to amplify the
specified region, which is usually
between 150-3,000 base pairs in length.
STEPS IN PCR OPERATION
The solution is heated to 95 C to unzip the double
helix DNA structure.
• The solution is cooled to 55 C to allow the primers
to bind to the ends of the
DNA.
• The solution is then reheated to 75 C which is the
optimal temperature for the Taq polymerase to

30. ADVANTAGES OF STRs OVER
RFLP/VNTR
STRs are currently the most popular type of
DNA fingerprint, since the whole
PCR process takes only a few
hours, compared to RFLP/VNTR probe
hybridization and film exposure which can
take several days. STRs can use much
smaller samples ofand quality of the DNA
DNA than
Thus, the integrity
RFLPs/VNTRs, and can factoruse partially
even with STRs than
sample is not as great a
degraded DNA to create a fingerprint
with the traditional methods of DNA
fingerprinting

31. DISADVANTAGE OF
STRs
The only disadvantage of the STR
approach is it is sensitive to
contaminating DNA, so usually the
STR approach is used first, followed
by a VNTR analysis if contamination
is suspected, and enough DNA is
available.

32. Practical Applications of
DNA
Fingerprinting
Paternity and
Maternity
Parent-child VNTR
pattern analysis
has been used to
solve standard
father-identification
cases

33. Criminal Identification and
Forensics
DNA isolated
from
blood, hair, skin
cells, or other
genetic evidence
left at the scene
of a crime can be

34. Diagnosis of Inherited
Disorders
Diagnose inherited disorders in
both prenatal and newborn
babies
These disorders may include
cystic
fibrosis, hemophilia, Huntington
's disease, familial

35. CONCLUSIO
N
DNA fingerprinting is the most sophisticated
way to identify living organisms.
DNA cannot easily be altered once it is left at
a
crimescene or deposited with a
mummy, which makes it a strong forensic
tool. RFLPs and VNTRs are the traditional
methods of fingerprinting DNA, which uses a
relatively large sample that uses the method
of probe hybridization to detect
polymorphisms in the