Biotechnologists in forensic science analyze biological evidence found at crime scenes, such as DNA, to create genetic profiles for identifying individuals. They extract DNA from samples and analyze regions that vary between people, like STRs and VNTRs, to develop a unique DNA fingerprint for each person. Techniques used include PCR, RFLP, and analysis of mitochondrial DNA, Y chromosomes, and Alu repeats. DNA profiling has become an important tool for forensic investigations.

1. ROLE OF
BIOTECHNOLOGIST
IN
FORENSIC SCIENCE

2. BIOTECHNOLOGY
◦Any technological application that uses
biological systems, living organisms, or
derivatives thereof, to make or modify
products or processes for specific use

3. FORENSIC SCIENCE
◦Forensic sciences involve the
scientific analysis and
documentation of evidence suitable
for legal proceedings

4. BIOTECHNOLOGIST
◦ To collect or process trace evidence such as hair, skin,
blood or semen samples, which is found at crime scenes
◦ Analyzing or creating DNA profiling or genetic
fingerprinting. Using the Sources of DNA include blood,
hair, semen, saliva, bone and tissue.

5. PRINCIPLE OF
DNA PROFILING
◦ The only difference between people (or any
animal) is the order of the base pairs.
◦ There are so many millions of base pairs in each
person’s DNA that every person has a different
sequence

6. DNA PROFILING
◦ Every person has a unique DNA profile. The only
exception to this is monozygotic twins.
◦ The chemical structure of everyone’s DNA is the same.
But the order of sequence vary for each one
◦ To identify individuals, forensic scientists scan 13 DNA
regions, or loci, that vary from person to person and use
the data to create a DNA profile of that individual (called a
DNA fingerprint).

7. DNA PROFILING
◦ There is an extremely small chance that another person has the same
DNA profile for a particular set of 13 regions.
◦ The technique of DNA fingerprinting is based on the analysis of two
types of highly variable sequences present in human genome:
◦ VNTR ( Variable Number Tandem Repeats) and
◦ STR (Short Tandem Repeats).
◦ By combining the information obtained from the analysis of more
VNTR or STR regions it is possible to obtain the distinctive profile of
a person.

8. TOOLS OF
FORENSIC SCIENCE
◦ Restriction Fragment Length
Polymorphism
◦ Polymerase Chain Reaction
◦ Random Amplified Polymorphic DNA
◦ Inter Simple Sequence Repeats analysis
◦ Mitochondrial DNA analysis
◦ Y chromosome markers analysis
◦ Alu repeats analysis

9. RESTRICTION FRAGMENT
LENGTH POLYMORPHISM
Restriction Fragment Length
Polymorphism (RFLP)
is a technique in which
organisms may be differentiated
by analysis of patterns derived from
cleavage of their DNA

10. 1.WHOLE BLOOD
OR STAINS
2.ISOLATE
NUCLEI 3.RECOVER
DNA
4.CUT DNA
INTO
FRAGMENTS
5.SEPARATE
FRAGMENTS
BY SIZE
6.TRANSFER DNA
TO
MEMBRANE
7.ADD
LABELED
DNA PROBE
9.WASHED
MEMBRANE10.DEVELOP X-RAY
FILM
11.ANALYZE
DNA
PROFILE
Restriction Fragment Length Polymorphism
[RFLP]
8

11. ADVANTAGE
◦ Highly robust methodology with good
transferability between laboratories.
◦ No sequence information required.
DISADVANTAGE
◦ Large amounts of DNA required.

12. POLYMERASE CHAIN
REACTION
◦ PCR is a technique that takes specific
sequence of DNA of small amount and
amplifies it to be used for further testing
◦ In vitro technique
◦ It amplify a lot of double-stranded DNA
molecules (fragments) with same (identical)
size and sequence by enzymatic method and
cycling condition.

15. ADVANTAGE
◦ Small amount of DNA is required per test
◦ Result obtained more quickly - usually within 1
day for PCR
◦ Usually not necessary to use radioactive material
(32P) for PCR

16. RANDOM AMPILIFIED
POLYMORPHIC DNA
◦ RAPD analysis is a PCR based molecular
marker technique. Single short
oligonucleotide primer is arbitrarily selected
to amplify a set of DNA segments distributed
randomly throughout the genome.

17. 1.BLOOD SAMPLE
2.ISOLATION
OF DNA
3.CUT DNA INTO
FRAGMENTS 4.SELECTION OF
RANDOM PRIMERS
5.DNA IS AMPLIFIED
THROUGH PCR
6.A MULTIPLE
NUMBER OF DNA IS
DEVELOPED
APPLICATION
• Use of non-specific primers to amplify
many regions of a sample DNA
• Can amplify upto 100 or more
loci in one sample
• Special importance in the
entomological investigations of corpses

18. INTER SIMPLE
SEQUENCE REPEATS
◦ Based on microsatellite primers
◦ No prior genomic information required
◦ Highly sensitive and informative
◦ It is PCR based analysis

19. MITOCHONDRIAL
DNA ANALYSIS
Preferred due to
• High copy number
• Lack of recombination
• Only maternal lineage identification

20. ROLE OF MT DNA
IN FORENSIC
◦ mt DNA will be used when "biological evidence may be
degraded [i.e. charred remains] or in small quantity“
◦ Cases in which evidence consists only of:
HAIR
BONE
TEETH
◦ Missing Persons Cases (use of skeletal remains)
◦ Establishing Individuals as suspects (hair evidence)

21. Y CHROMOSOME
ANALYSIS
◦ For gender discrimination
◦ Identity fixation in rape cases
◦ For paternal lineage analysis

22. Alu repeats analysis
◦ Transposable elements
◦ Site for Arthrobacter luteus (Alu) restriction
endonuclease
◦ Can be present/absent on same
chromosome among different families
◦ Identification of population ancestral lineage

23. APPLICATION
◦ Sample analysis
◦ Lineage analysis
◦ Suspect identification
◦ Anthropological studies
◦ Population genetics studies