Biotechnology is one of the branch that is contributing in forensic science. There are many tools in biotechnology that helps in solving cases in forensic.

1. Biotechnology tools in
forensic science
Malsha Kularathna
BSc(Hons)Biotechnology (UG)
AFRS - Volunteer

2. Content
1. Introduction
2. DNA Sequencing
3. PCR Machine
4. Gel Electrophoresis Apparatus
5. UV – VIS Spectroscopy
6. Microarray
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3. Introduction
What is Forensic Biotechnology?
 Forensic biotechnology refers to the application of biotechnology techniques and methods for
investigating legal cases. This field combines principles of biology, genetics, and molecular biology.
 Forensic biotechnology can be used in a variety of contexts, including criminal investigations,
paternity testing, and identification of human remains.
 Some common techniques and tools used in forensic biotechnology include,
• DNA Sequencing machine
• PCR (polymerase chain reaction) machine
• Gel Electrophoresis Apparatus
• UV-VIS Spectrometer
• Microarray
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4. 01. DNA Sequencing
 DNA sequencing is the process of determining the exact order of nucleotides in a DNA sample. In forensic
science DNA sequencing is used to determine paternity, and analyse genetic mutations.
 The steps involved in DNA sequencing using a DNA sequencing machine are as follows:
1. Sample Preparation
2. Library Preparation
3. Loading the DNA Sequencer
4. Sequencing
5. Data Analysis
• Sample Preparation: The DNA sample is extracted from the biological material, purified, and quantified to
ensure that there is enough DNA for sequencing. The sample is then fragmented into smaller pieces for
sequencing.
• Library Preparation: The fragmented DNA is ligated with adapters that allow it to be amplified and
sequenced. The resulting library is amplified through PCR to create multiple copies of the DNA fragments.
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5. • Loading the DNA Sequencer: The DNA library is loaded into the DNA sequencer, where it is
immobilized on a flow cell or a sequencing chip.
• Sequencing: The sequencing machine adds nucleotides to the immobilized DNA fragments, one at
a time, and records the fluorescent signals generated as each nucleotide is incorporated. The
sequencing machine then identifies the specific sequence of each fragment based on the order of
the fluorescent signals.
• Data Analysis: The raw sequencing data is then processed using specialized software to remove
errors, filter out low-quality reads, and assemble the reads into a complete sequence.
Figure 01 – DNA Sequencing Machine 5

6. 02. PCR Machine
 Polymerase chain reaction (PCR) machines are used to amplify small amounts of DNA into larger
quantities that can be analysed.
 PCR is often used to generate DNA profiles from very small or degraded samples, such as those found
in bones or hair.
Figure 02 – PCR Machine Figure 03 – Parts of PCR Machine
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7.  The PCR method requires the following four reagents or chemicals:
i. DNA or RNA sample
ii. DNA primers:- short single-stranded DNA molecule that promotes synthesis of a complementary strand of nucleotides
iii. DNA polymerase:- an enzyme that aids in the synthesis of a complementary strand of DNA
iv. Nucleotide solution mix containing
 The PCR process has 4 steps:
i. Denaturation
ii. Annealing
iii. Extension
iv. Repeated cycles
• Denaturation: The double-stranded DNA is heated to a high temperature (typically 94-98°C) to separate the two
strands of DNA.
• Annealing: The temperature is lowered to allow the primers to anneal (bind) to the complementary single-stranded
DNA templates. The primers are short pieces of DNA that are designed to bind to the specific sequence of DNA that is
to be amplified. 7

8. • Extension: The temperature is raised to a temperature that is optimal for the DNA polymerase enzyme to add
nucleotides to the 3' end of each primer, extending the DNA strands. The DNA polymerase enzyme extends the
primers in a 5' to 3' direction, using the single-stranded DNA template as a template for the new DNA strand.
• Repeated cycles: The denaturation, annealing, and extension steps are repeated multiple times (usually 20-40
cycles) to amplify the DNA segment of interest exponentially. The number of DNA segments is doubled with
each cycle of PCR, resulting in a very large number of copies of the targeted DNA segment.
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9.  In forensic science, PCR is used for various applications.
• DNA profiling : This technique is used in forensic investigations to identify suspects or to match DNA
samples collected from a crime scene.
• Forensic paternity testing : This technique is used in cases where the identity of the biological father
needs to be established.
• Detection of pathogens : PCR is used to detect the presence of pathogens such as viruses or bacteria in
forensic samples.
Figure 04 – DNA paternity testing
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10. 03. Gel Electrophoresis Apparatus
 Gel electrophoresis is a laboratory technique used to separate & analyse mixtures of biological
macromolecules such as DNA, RNA & proteins based on their size, charge & shape.
Figure 05 – Parts of Gel Electrophoresis
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11. Procedure of Gel electrophoresis apparatus
 Preparation of the gel
 Loading the gel into the electrophoresis tank
 Loading the biological sample
 Applying the electric field
 Running the electrophoresis
 Staining the gel
 Documenting the results
Figure 06 – Procedure of Gel Electrophoresis 11

12.  Gel electrophoresis is used in forensic science to analyse DNA evidence , such as in criminal
investigations, analysis of mitochondrial DNA and paternity testing.
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13. 04. UV-VIS Spectroscopy
 The best analytical method for analysing a variety of evidence, including bodily fluids, narcotics, and
trace components discovered at the scene of the crime, is spectrophotometry.
1) Identification of smokeless powder using spectroscopy
When no weapon is discovered in a shooting crime, smokeless powder will be the key piece of forensic evidence.
Figure 06 - Composition of smokeless powder
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14. 2) A UV-Vis spectrophotometer for fiber analysis
Fiber is a type of evidence found at crime scenes, similar to hair. Fibers as evidence have probative value
in forensic science because they establish linkages or associations between the suspect and the victim.
Figure 07 – Fiber as evidence
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15. 3) Spectroscopy technique to analyze automotive paints
Paint fragments found at the scene of the crime can be used as forensic evidence in cases of automobile accidents,
vandalism, and burglaries. This evidence aids in identifying crimes.
4) Spectroscopy for forensic toxiology
The investigation of biological materials to identify toxins or medications is known as forensic toxicology.
Toxicology provides the information what type of substance and the amount of substance used which is potential
effect for the person illness or death
Figure 08- UV Spectroscopy 15

16. 05.Microarrays
 A microarray is a laboratory tool used to simultaneously monitor the expression of thousands of
genes.
 They can be used in forensic science to identify genetic variations and compare DNA samples.
Figure 09 - Microarray
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17.  Microarrays can be used for a wide range of forensic applications, including:
• DNA identification: Microarrays can be used to identify individuals by comparing their DNA profiles to those
in a database.
• Ancestry testing: Microarrays can be used to identify an individual's ancestry by comparing their DNA to
reference populations.
• Paternity testing: Microarrays can be used to determine paternity by comparing the DNA of an alleged father
to that of a child.
• Forensic DNA phenotyping: Microarrays can be used to predict physical characteristics of an individual based
on their DNA.
Figure 10 – Microarray technique
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18. References
1. DNA Sequencing. (n.d.). Genome.gov. https://www.genome.gov/genetics-glossary/DNA-Sequencing
2. Wikipedia contributors. (2023). DNA sequencing. Wikipedia.
https://en.wikipedia.org/wiki/DNA_sequencing
3. Karki, P. (2022). PCR Machine- Principle, Parts, Steps, Types, Uses, Examples. Microbe Notes.
https://microbenotes.com/pcr-machine-principle-parts-steps-types-uses-examples/
4. gel electrophoresis | Learn Science at Scitable. (n.d.). https://www.nature.com/scitable/definition/gel-
electrophoresis-286/
5. SMACgig World. (2022). Spectroscopy and Forensics. www.smacgigworld.com.
https://www.smacgigworld.com/blog/spectroscopy-and-forensics.php
6. microarray | Learn Science at Scitable. (n.d.). https://www.nature.com/scitable/definition/microarray-
202/
7. Nhgri. (2019). DNA Microarray Technology Fact Sheet. Genome.gov. https://www.genome.gov/about-
genomics/fact-sheets/DNA-Microarray-Technology
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19. THANK YOU!
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