Context:
What is DNA fingerprinting? | The Hindu Explained
DNA Fingerprinting:
- DNA fingerprinting: Scientific technique to identify individuals by their unique genetic profiles.
- Uses short tandem repeats (STRs) in DNA to identify individuals.
- Applicable for genetic relationships, criminal investigations, and forensic identification.
- DNA samples can be obtained from blood, saliva, sweat, semen, skin cells, bones, or teeth.
- Highly reliable, as every person (except identical twins) has a unique DNA profile.
Applications:
- Forensic science: Identifies criminals using DNA evidence from crime scenes.
- Paternity testing: Establishes biological relationships.
- Disaster victim identification: Identifies mortal remains.
- Medical applications: Assists in organ transplantation compatibility.
- Exoneration of wrongly accused: Used for retrials and cold cases.
DNA Polymorphism:
- DNA polymorphisms: Small variations in DNA sequences that differentiate individuals.
- Result from differences in inherited DNA from both parents.
- Essential for tracing ancestry, identifying individuals, and understanding genetic diversity.
Molecular Basis of DNA Polymorphism:
- Arises from mutations like SNPs (Single Nucleotide Polymorphisms) and VNTRs (Variable Number Tandem Repeats).
- Involves variations in non-coding and coding regions of DNA.
- Impacts gene expression, protein function, and phenotype variability.
- Caused by genetic recombination, replication errors, or environmental factors.
Evolutionary Significance:
- Enhances genetic diversity, aiding adaptation to environmental changes.
- Crucial for natural selection and evolutionary fitness.
- Helps trace ancestry and evolutionary relationships among populations.
- Explains disease susceptibility and resistance in different genetic groups.
Short Tandem Repeats (STRs):
- STRs: Repetitive DNA sequences that vary in length between individuals.
- Each STR comprises short repeating units of DNA bases (A, T, G, C).
- Variations in repeat numbers form the basis of DNA fingerprinting.
- STR analysis is widely used in criminal investigations and genetic identification.
Ethical and Legal Issues:
- Raises concerns about genetic privacy and potential misuse of genetic data.
- Issues of informed consent and ownership of genetic information.
- Potential for genetic discrimination in insurance and employment.
- Legal challenges in forensic applications and ancestry testing.
DNA Copying (PCR Process) Vs DNA Fingerprinting
| Aspect | DNA Copying (PCR Process) | DNA Fingerprinting |
| Definition | Amplifies a specific DNA sequence. | Identifies individuals based on unique DNA patterns. |
| Purpose | Generates multiple DNA copies for research, diagnosis, and forensics. | Establishes identity, verifies relationships, and solves forensic cases. |
| Key Process | Polymerase Chain Reaction (PCR). | STR analysis and Capillary Electrophoresis. |
| Steps Involved | Denaturation (strands separate), Annealing (primers bind), Extension (synthesizing strands). | DNA extraction, STR amplification, DNA fragment separation, creation of DNA profile. |
| End Product | Millions of identical copies of a specific DNA segment. | A unique DNA pattern (fingerprint) for an individual. |
| Use in Forensics | Amplifies DNA from crime scene samples for analysis. | Compares DNA from a crime scene with a suspect’s DNA. |
| Use in Medicine | Aids disease diagnosis and genetic research. | Assists in organ transplant compatibility and hereditary disease identification. |
| Data Output | Large amounts of identical DNA for study. | A unique STR profile to distinguish individuals. |
Source: The Hindu
Previous Year Question
‘Aerial metagenomics’ best refers to which one of the following situations?
[UPSC Civil Services Exam – 2023 Prelims]
(a) Collecting DNA samples from air in a habitat at one go
(b) Understanding the genetic makeup of avian species of a habitat
(c) Using air-bome devices to collect blood samples from moving animals
(d) Sending drones to inaccessible areas to collect plant and animal samples from land surfaces and water bodies
Answer: (a)