Explains about DNA fingerprinting benefits ad involvement of modern world. Here you can learn details about DNA fingerprinting and its principle, methods,applications and disadvantages.

1. DNA Fingerprinting
Benefits And Involvement Of
Modern World
By
Sushmitha M

2. Index
● Introduction
● History
● Necessity
● Principle
● Samples needed
● Methods involved
● RFLP steps
○ Isolation
○ Restriction digestion
○ Gel electrophoresis
○ Southern blotting
○ Selection of probes
○ Hybridization
○ Photography
● Advantages&Limitations
● PCR steps
○ Isolation
○ PCR amplification
○ Agarose gen
electrophoresis
○ UV transilimination
○ Graphical
representation
● Advantages and
limitations
● Applications

3. Introduction
● Lab technology used to
determine probable identity of
person based on nucleotide
sequence of human DNA.
● Isolation and identification of
variable element within base
pair seq of DNA.
● Used to establish link between
biological evidence & suspect
in criminal investigation.
Other names
● DNA typing
● DNA profiling
● Genetic fingerprinting
● Genotyping
● Identity testing

4. History of DNA fingerprinting
● 1986 - Dr. Alec. J . Jeffrey- father of DNA
fingerprinting- first used in forensic science.
● 1988 - Lal Ji Singh - father of dna
fingerprinting in India - use probe to solve case
of parentage disputes.
● 1991- singh produce 1st DNA fingerprinting
based evidence in Indian court
● Now - used to solve 100s and 1000s of criminal
and civil cases

5. Necessity
● For criminal investigation of murder case, UK government ask alec
Jeffrey to verify the suspect confesion that he was responsible for two
rape and murder case.
● In india its done for paternity testing.
● Used for detection of mutation and individual identification.

6. Principle
● DNA of every animal and plants 99% same - bulk region, 1% differ
from one another - Satellite region - two types
○ Micro satellite/ STRs- short tandem repeats
○ Mini satellite / VNTRs- variable number of tandem repeats.
● VNTRs and STRs play important role - inherited from 50%- mother &
50% - father which distinguish one person from another.
● Change in nucleotide cause few more cleavages or abolish cleavages in
particular site during restriction digestion- basic of DNA fingerprinting.

7. Principle

8. Samples needed
● Blood
● Finger Nails
● Hair roots
● Tissues / cells from internal
organ including brain
● Teeth
● Small amount of sample
enough.

9. Methods involved in DNA fingerprinting
Methods
RFLP- Restriction Fragment
Length Polymorphism
PCR - Polymerase
Chain Reaction
Produce multiple
copies of specific
STR
Exploits variations in
homologous DNA sequence
to distinguish individuals

10. Steps involved in RFLP
Isolation of DNA Restriction Digestion Gel electrophoresis
Southern blotting
Selection of DNA
probe
Hybridization
Photography

11. Isolation of DNA
● Samples collected from crime scene and suspect.
● DNA isolated from sample by centrifugation by adding buffer.
● Sample may be hair root, blood, skin, etc..

12. Restriction digestion
● Isolated DNA treated with
specific restriction enzyme-
cut DNA into small
fragments.
● Those fragments having
variable lengths containing
both bulk and satellite region
of DNA.

13. Gel electrophoresis
● Samples loaded into wells under influence of electric field.
● DNA fragments are negatively charged move towards positive pole.
● Movement depends on length of fragments results in band formation.

14. Southern blotting
● Separated DNA transferred to
nylon membrane or
nitrocellulose filter paper.
● Placing it over gel and soaking
them in buffer for overnight
● ds DNA splits into ssDNA by
alkali treatment.

15. Southern blotting

16. Selection of DNA probes
● Known sequence of single stranded DNA which complement to VNTR
of sample DNA was prepared.
● Probes can be selected according to five methods
○ Cross hybridization
○ deltaT(m)
○ Folding
○ Position
○ Low complexity
● Which is obtain from organism or by cDNA library.
● Probe is labelled with radioactive isotopes

17. Hybridization
● Process in which two complementary ssDNA
bond together to form dsDNA.
● Probe DNA added to nitrocellulose paper
containing host DNA.
● ssDNA probe pairs with complementary base
sequence on host DNA.
● DNA-DNA hybrids formed on nitrocellulose
paper.
● Remaining ssDNA probe washed off.

18. Photography
● Nitrocellulose paper photographed
on X-ray film by autoradiography.
● Film is analysed to determine the
presence of hybrid DNA.
● Comparing the sample collected
from crime scene and suspects
reveals real culprit.

19. Steps involved in RFLP

20. Advantage and Limitations
● RFLP more accurate than PCR because size of sample used more, use of
fresh DNA sample and no amplification contamination.
● Co- dominance - investigators easily distinguish heterozygotes from
homozygotes.
● However it require long time period for analysis and its costly.
● It can’t be stored.

21. Steps involved in PCR
Isolation PCR
amplification
AGE Graphical
representation
UV-
transillumination

22. Isolation of DNA
● Samples collected from child and parents.
● DNA isolated from sample by centrifugation by adding buffer.
● Sample may be hair root, blood, skin, etc..

23. PCR amplification
● Technique that amplify DNA into
multiple copies using heavy heat.
● Selection of primer is very important
step.
● Selecting specific primer to copy
particular gene.
● Primer must be complement to the STR
region of child DNA.
● Primer will attach to suspect DNA
which having genes inherited to child.

24. Agarose Gel Electrophoresis
● Samples loaded into wells under influence of electric field.
● DNA fragments are negatively charged move towards positive pole.
● Movement depends on length of fragments results in band formation.

25. UV Transillumination
● Visualize target DNA.
● Same sized bands will appear for child and real father.

26. Graphical representation
● Separate graph was drawn against frequency and paternity index value
for child and their suspected parents

27. Steps involved in PCR method

28. Advantages and Limitations
● Small amount of specimen is sufficient
● Takes shorter time to complete
● Less costlier than RFLP method.
● However it is less accurate than RFLP
● Possibility of amplification contamination.

29. Application of DNA fingerprinting
● Criminal investigation
● Paternity test
● Detecting mutation which cause diseases
● Individual identification
● Track blood relations
● Study biodiversity of species
● Track genetically modified crops

30. QUESTIONS

31. THANK
YOU