DNA Finger Printing | Agriculture Optional Notes for UPSC PDF Download

DNA Fingerprinting

DNA fingerprinting is a laboratory method employed to establish a person's likely identity based on unique nucleotide sequences found in certain regions of human DNA. These nucleotide sequences belong to specific segments of human DNA known as repetitive DNA, and they are distinctive for each individual. DNA fingerprinting relies on these repetitive DNA sequences to determine a person's probable identification.

Professor Sir Alec Jeffreys invented DNA fingerprinting in 1984 when he realized that variations in human DNA, particularly in minisatellites, could be detected. This technique allows for the simultaneous detection of numerous minisatellites in the genome, resulting in a distinct pattern unique to each individual. This unique pattern is referred to as a DNA fingerprint.

Lalji Singh is recognized as the pioneer of DNA fingerprinting in India. He developed DNA fingerprinting for use in criminal investigations at the Centre for Cellular and Molecular Biology (CCMB) in Hyderabad in 1988. In 1989, the Kerala Police utilized DNA fingerprinting in a case for the first time.

What is DNA?

DNA, or deoxyribonucleic acid, is present within every cell in your body and functions as a sequence of chemical compounds that unite to establish enduring life plans.

• These chemical elements, referred to as bases, encompass four varieties: adenine (A), thymine (T), guanine (G), and cytosine (C). 
• They combine in pairs to create base pairs (A-T and C-G). Your DNA incorporates approximately 3 billion of these pairs. The specific arrangement of these pairs serves as instructions for your cells on how to duplicate themselves.

A genome refers to the full collection of your genetic compounds.

• Over 99.9% of the genome is the same for everyone, and it's 100% identical for identical twins.
• The minuscule portion of the genome that differs is what accounts for the physical and mental distinctions between individuals.

Minisatellites

• Minisatellites are brief sequences of repetitive DNA, typically 10-60 base pairs in length.
• They display more diversity from one person to another compared to other parts of the genome.
• This diversity is evident in the count of repeated units or 'stutters' in the minisatellite sequence.
• The initial minisatellite was identified in the year 1980.

DNA Profiling

• Contemporary DNA profiling, known as STR analysis, employs microsatellites rather than the minisatellites utilized in DNA fingerprinting.
• Microsatellites, also referred to as short tandem repeats (STRs), are shorter versions of minisatellites, typically consisting of two to five base pairs.
• Similar to minisatellites, STRs are repeated multiple times across the human genome, forming patterns like 'TATATATATATA.'
• Individuals inherit half of their DNA from their mother and half from their father, making STRs inherited from parents to their offspring.

How is DNA fingerprinting done?

DNA fingerprinting uses chemicals to separate strands of DNA and reveal the unique parts of your genome.
The results show up as a pattern of stripes that can be matched against other samples.
To get your DNA fingerprint, you would give a sample of cells from your body.

• This can come from a swab inside your mouth, from your skin, the roots of your hair, or your saliva, sweat, or other body fluids.
• Blood is usually the easiest way.
• Lab technicians treat the sample with chemicals to separate the DNA, which is then dissolved in water.

Applications of DNA Fingerprinting

DNA profiling is primarily employed in legal cases and judicial matters related to criminal investigations or disputes.
Its applications include:

• Linking a piece of evidence to an individual or excluding someone as a suspect.
• Determining familial relationships, such as parents, siblings, and other relatives.
• Identifying a deceased body that's severely decomposed and unrecognizable.
• Matching organ donors' tissues with transplant recipients.
• Detecting inherited diseases within families.
• Contributing to the research of cures for hereditary conditions.

In forensic science, DNA profiles are particularly valuable because even a small trace of human material left at a crime scene can be adequate for identifying an individual.
The United Kingdom was the first nation to establish a national database of DNA profiles in 1995.

DNA fingerprinting in agriculture

• DNA fingerprinting is utilized in combination with conventional genetic analysis of family lineages and breeding information to detect DNA markers that are inherited alongside significant characteristics. This procedure is occasionally known as marker-assisted selection.
• Recombinant DNA technology has enhanced plant growth by improving nitrogen fixation efficiency, replicating bacterial genes, and incorporating them into plant cells.
• Some plants have been genetically modified to possess resistance to caterpillars, pests, and viruses by introducing genes that provide resistance into their genomes.

DNA Fingerprinting in India

The Centre for DNA Fingerprinting and Diagnostics (CDFD) is an Indian biotechnology research institution situated in Hyderabad, India, and it is administered by the Department of Biotechnology, Ministry of Science and Technology, Government of India.

According to Article 51A(h) and (j) of the Indian Constitution, citizens have a responsibility to promote scientific knowledge, humanism, the spirit of inquiry, and reform, as well as to pursue excellence in individual and collective endeavors. Therefore, the Indian Parliament can legitimately support and advance the use of technical and scientific methods to expedite the criminal justice system, as specified in the union list.

Section 9 of the Indian Evidence Act of 1872 addresses "facts necessary to explain or introduce a fact in issue or relevant fact."

In specific situations, such as cases of rape, the Criminal Procedure Code (CrPC) through Section 53-A allows for the examination of an accused individual by a medical practitioner, including the collection of bodily substances for DNA fingerprinting.