Description aboutDNA Fingerprinting 1.pdf

Description about DNA fingerprinting

1. Govt.J.Y.Chhattisgarh
College Raipur (C.G)
Department Of Botany
Topic –DNA Fingerprinting
Presented By- Guided By-
Janhavi Dr. Satendra Kumar
Induria
MSc 3
rd
Semester

2. Synopsis
•Introduction
•Principle
•Methodology
•Application
•Advantages
•Disadvantages
•References

3. Introduction
•Distinguishing the individuals according to their DNA prints pattern, is
called DNA fingerprinting.
•DNA Fingerprinting is a forensic technique used to identify individuals
by characteristics of their DNA.
•The process of DNA fingerprinting was invented by Alec Jeffrey at the
University of Leicester in 1985.
•Also called DNA Profiling or Molecular Fingerprinting.

4. Principle
•The principle behind DNA fingerprinting is that the DNA in the nucleus of
somatic cells is unique to each individual, except for identical twins.
•This is because while over 99% of DNA sequences are the same across
all humans, there are regions called variable number tandem repeats
(VNTRs) or short tandem repeats (STRs) that differ between individuals.
•Satellite DNA is a non-coding region of eukaryotic cells having tendem
repeats of a sequence. It is also called mini-satellite. It is rich in GC pairs
and 9-40 bp in size.

5. Methodology
•DNA fingerprinting involves the
following steps-
1.Isolation of cell DNA
2.Restriction digestion or DNA cutting
3.Gel electrophoresis
4.Southern blotting and plucking
5.Selection of DNA probe
6.Filter hybridization
7.Autoradiography
8.Analysis of DNA print pattern.

6. 1. Isolation of DNA
•The cell DNA is obtained from blood
or semen clotted on cloths, vaginal
swabs taken from rape victims, hairs
or fresh cells or blood.
•DNA is isolated from the source
material and the suspected
individuals.

7. 2. Restriction digestion or DNA cutting
•The DNA is cut into
fragments using restriction
enzymes.
•Each restriction enzyme cuts
DNA at a specific base
sequence.
•As a result minisatellites get
released from the cell DNA.

8. 3. Gel Electrophoresis
•Each DNA restriction digest of the
resource persons and source material, is
poured into a well of an electrophoresis
pel and electrophoresed.
•DNA Fragments separated by length
•DNA (negatively charged)
•Moves towards +ve terminal
•Shorter fragments move faster.

9. 4. Southern Blotting and Packing
•The separated DNA fragments are transferred to a
nylon membrane or a nitrocellulose filterpaper by
placing it over the gel.
•This process is called southern blotting.
•The nitrocellulose filter having DNA fragment in
between dry filter papers at high temperature called
packing.

10. 5. Selection of DNA Probe
•In the USA. DNA probes constructed by Alec Jeffrey used for DNA
fingerprinting.
•However, these probes are not available to India.
•Dr. Lalji Singh at the Centre for cellular and Molecular Biology in
Hydrabad has developed a DNA probe from minisatellite DNAand named
it BKm probe.
•The Bkm probeis being used for DNA fingerprinting in India.

11. 6. Filter Hybridization
•The nitrocellulose filteris placed in an alkali solulion to denature the
duplex DNA fragments.
•DNA is split into single strands.
•Then it is placed in the hybridization solution containing the probe DNA.
•Radioactive probe DNA binds with appropriate minisatellites and forms
duplex DNA.

12. 7. Autorediography
•After hybridization, the filter in washed with a wash solution
to remove unbound probes.
•X-ray film placed over filter paper.
•Radioactivity probes makes dark spots on film.
DNA Fingerprinting
pattern

13. 8 . Analysis of DNA print pattern
•In the case of rape and murder, all bands of seminal DNA or hair-DNA should
match perfectly with DNA print of ratoused. If the match is 100%, the
indiviatual is found to responible for the victim. All bands of source material
never match with the bands of DNA print of any person who didn’t involve in
the case.
•For determining the parentage of a child 50% of bands in the child’s DNA
print should be match with the father’s DNA print and rest of the bands
should match with mother’s DNA print.

15. Example
•Violent murder case
•The forensics team retrieved a blood sample from the crime
scene.
•They prepared DNA profiles of the blood sample, the victim
and a suspect as follows:

16. DNA Profile
V victim
S sample from crime
scene
S1 suspect 1
S2 suspect 2
S3 suspect 3

17. Applications
1.Individuality:- like skin finger printing, DNA finger printing can help to distinguish one
human being from another with exception of monozygotictwins.
2.Paternity/maternity Disputes:-DNA fingerprinting can identify the real genetic mother,
father and the offspring.
3.Human Lineage:- DNA from various probables is being studied to find out human lineage.
4.Hereditary Diseases:- The technique is being used to identify genes connected with
hereditary diseases.
5.Forensics science:- Detection of crime and legal pursuits.
6.Sociology:- Identify racial grips, their origin, historical migration and invasions.
7.Diagnosis of inherited disorders:- Helps diagnose disorders in both prenatal and new born
babies.
8.Plant breeding :- DNA fingerprinting can be used to identify varieties of plants, protect
varieties, and settle disputes.
9.Detection of AIDS:- By comparing the band of HIV “RNA” (converted to DNA using
RTPCR) with the bands form by the man’s blood, person suffering with AIDS can be
identified.

18. Advantages
•DNA profiling is an ideal method for confirming an identity
with absolute certainty.
•It’s easy and painless to obtain a specimen for testing.
•Atborough, scientific test can be conducted in as little as 48
hours.
•DNA testing is affordable and reliable.
•DNA profiles can be used to place suspects at a crime scene.

19. Disadvantages
•Contamination: DNA from external sources can be introduced
at a crime scene or lab, leading to errors.
•Mixed samples: It can be difficult to separate individual
profiles from a DNA sample that contains multiple
contributors.
•Costly: DNA fingerprinting requires expensive laboratory
equipment and skilled personnel.
• Crime framing: Criminals can plant DNA at a crime scene to
frame an innocent person.

20. References
•B.D.Singh, Kalyani publishers,
Biotechnology Expanding Horizons,
Third edition, chapter 13,
Biotechnology and Health Care, pg
no. 565-574.
•V. Kumaresean, Saras publication,
Biotechnology, Sixth edition,
chapter 25, DNA Fingerprinting, pg
no. 306-313.
•Biotechnology by U.Satyanarayana.