Microsatellite DNA is used in the case of which one of the following?
Contents17
- AStudying the evolutionary relationships among various species of fauna
- BStimulating 'stem cells' to transform into diverse functional tissues
- CPromoting clonal propagation of horticultural plants
- DAssessing the efficacy of drugs by conducting series of drug trials in a population
Show answer
Answer: (A) Studying the evolutionary relationships among various species of fauna
Microsatellite DNA (also called Short Tandem Repeats or STRs) consists of short, repeating DNA sequences.
Since the number of repeats varies between individuals, microsatellites are very useful for DNA fingerprinting in forensic investigations and for studying genetic relationships in populations.
Answer is (a) Forensic science.
Microsatellite DNA sequences vary between individuals and populations, making them powerful molecular markers for tracing evolutionary relationships and genetic diversity across species.
UPSC is testing whether students can distinguish microsatellites (used for genetic analysis) from other biotechnology tools like stem cell therapy, tissue culture, and pharmacogenomics.
Microsatellite DNA & Short Tandem Repeats
Science And Technology Microsatellite DNA
Microsatellite DNA: Structure, Properties & Applications
Microsatellite DNA = Short Tandem Repeats (STRs) - short DNA sequences repeated multiple times
Number of repeats varies between individuals, making it ideal for DNA fingerprinting
Primary use: studying evolutionary relationships and forensic investigations
Found throughout genomes of most organisms, highly polymorphic in nature
What are Microsatellites
Microsatellite DNA consists of short DNA sequences (typically 2-6 base pairs) that are repeated in tandem multiple times. Also called Short Tandem Repeats (STRs), these sequences show high variability in the number of repeats between different individuals, making them powerful genetic markers.
Key Properties
Property | Description | Example |
|---|---|---|
Repeat Unit | Short sequences of 2-6 base pairs | CA, GATA, AAAG |
Length Variation | Number of repeats differs between individuals | One person: (CA)₁₅, Another: (CA)₂₃ |
Inheritance | Follow Mendelian patterns, co-dominant | Both parental alleles detectable |
Distribution | Found throughout genome, non-coding regions | Every 2-3 kb in human genome |
Applications Comparison
Application | How STRs are Used | Why Effective |
|---|---|---|
Evolutionary Studies | Compare STR patterns across species | Reveals genetic distances & relationships |
Forensic Science | Match DNA from crime scenes | Individual-specific patterns |
Paternity Testing | Compare child-parent STR profiles | Inherited from both parents |
Population Genetics | Study genetic diversity in groups | High polymorphism reveals structure |
Question Connection
This question tests understanding of microsatellite applications. Option A is correct because STRs are extensively used to study evolutionary relationships - the variation patterns reveal how closely related different species are. The other options involve different biotechnology tools entirely.
Trap: Confusing microsatellites with stem cell markers - STRs don't stimulate cellular transformation
Trap: Thinking microsatellites promote plant propagation - they're analytical tools, not growth promoters
Trap: Mixing up with pharmacogenomics - drug efficacy studies use different genetic markers
Memory Aid: Micro-SATELLITE = orbits around genome, mapping relationships between organisms
DNA Fingerprinting & Forensic Applications
Science And Technology
DNA Fingerprinting: Principles & Forensic Applications
DNA fingerprinting uses STR markers to create unique genetic profiles for individuals
Standard forensic panels use 13-20 STR loci for human identification
Probability of two unrelated individuals having identical STR profile: 1 in billions
DNA Fingerprinting Process
%%{init: {"flowchart": {"wrappingWidth": 460}}}%%
flowchart TD
s1["`****DNA Extraction****
Isolate DNA from biological samples (blood, saliva, hair)`"]
s2["`****PCR Amplification****
Amplify specific STR loci using fluorescent primers`"]
s3["`****Electrophoresis****
Separate amplified fragments by size using capillary electrophoresis`"]
s4["`****Profile Generation****
Create STR profile showing allele sizes at each locus`"]
s5["`****Database Comparison****
Compare with known profiles or forensic databases`"]
s1 --> s2
s2 --> s3
s3 --> s4
s4 --> s5Forensic Applications
Application | Sample Types | Key Challenge |
|---|---|---|
Criminal Investigation | Blood, semen, saliva from crime scenes | Degraded or mixed DNA samples |
Paternity Testing | Buccal swabs from child and alleged father | Mutation rates in STR loci |
Mass Disaster Victim ID | Any available tissue, bone fragments | Severely degraded DNA |
Cold Case Resolution | Archived evidence, exhumed remains | DNA degradation over time |
Indian Forensic System
National DNA Database operational since 2016 under Bureau of Police Research & Development
DNA Technology (Use and Application) Regulation Act, 2019 governs forensic DNA use in India
Centre for DNA Fingerprinting (CDFD), Hyderabad - premier national facility for DNA analysis
Used in high-profile cases including 26/11 Mumbai attacks victim identification
Trap: Assuming DNA fingerprinting = whole genome sequencing - only specific STR loci are analyzed
Trap: Confusing STR-based profiling with mitochondrial DNA analysis used for maternal lineage
Legal Trap: DNA evidence is probabilistic, not absolute proof - requires statistical interpretation
Molecular Evolution & Phylogenetic Analysis
Science And Technology evolutionary relationships species
Using Genetic Markers to Study Evolutionary Relationships
Microsatellites reveal evolutionary relationships by comparing genetic variation patterns across species
Genetic distance calculated from STR differences indicates how recently species diverged
More similar STR patterns = closer evolutionary relationship
Molecular Evolution Principle
Species that diverged recently share more similar STR patterns than those that separated long ago. The rate of mutation in microsatellite regions acts like a molecular clock, allowing scientists to estimate when evolutionary lineages split.
Genetic Markers in Evolution Studies
Marker Type | Evolution Timeframe | Best For | Example Use |
|---|---|---|---|
Microsatellites (STRs) | Recent divergence (1000s-100,000s years) | Population genetics, subspecies | Tiger subspecies relationships |
Mitochondrial DNA | Medium timeframe (100,000s-millions years) | Species-level phylogeny | Human migration patterns |
Nuclear genes | Deep time (millions-billions years) | Major taxonomic groups | Mammalian evolution |
Whole genome | All timescales | Comprehensive analysis | Primate evolutionary tree |
Applications in Conservation
# STRs in Conservation Biology
## **Species Identification**
- Wildlife trafficking cases
- Illegal trade detection
- Taxonomic verification
## **Population Structure**
- Migration patterns
- Breeding populations
- Genetic bottlenecks
## **Breeding Programs**
- Avoid inbreeding
- Maintain genetic diversity
- Captive breeding successIndian Wildlife Studies
Tiger conservation: STR analysis revealed distinct populations across Indian reserves, guiding corridor planning
Asian elephant: Microsatellite studies show fragmented populations due to habitat loss
Snow leopard: STR markers used to estimate population size in Himalayan regions using non-invasive sampling
Trap: Confusing phylogeny (evolutionary relationships) with taxonomy (classification system)
Trap: Assuming genetic similarity always equals morphological similarity - evolution can be convergent
Key Point: STRs show recent evolutionary history better than ancient divergences
Biotechnology Applications in Medicine & Agriculture
Science And Technology stem cells clonal propagation drug trials
Key Biotechnology Applications: Why They Don't Use STRs
Stem cell transformation uses growth factors and signaling molecules, not STR markers
Plant clonal propagation relies on tissue culture techniques and plant hormones
Drug efficacy trials use pharmacokinetic studies and clinical endpoints, not STR analysis
Biotechnology vs STR Applications
Field | Actual Tools Used | Purpose | Why Not STRs |
|---|---|---|---|
Stem Cell Biology | Growth factors, cytokines, scaffolds | Direct cellular transformation | STRs are markers, not functional agents |
Plant Propagation | Auxins, cytokinins, tissue culture | Promote cell division & differentiation | STRs don't influence plant growth |
Drug Development | Biomarkers, clinical endpoints | Measure drug effects on disease | STRs show inheritance, not drug response |
Gene Therapy | Viral vectors, CRISPR, plasmids | Deliver therapeutic genes | STRs are repetitive, non-coding sequences |
Correct Applications Overview
Stem cells: Require transcription factors (Oct4, Sox2, Nanog) and specific culture conditions for differentiation
Plant cloning: Uses meristem culture, somatic embryogenesis, and micropropagation techniques
Drug trials: Employ pharmacokinetic studies, biomarker analysis, and population pharmacogenomics
Trap: Thinking all genetic tools work for all biotechnology applications - each field has specific techniques
Trap: Confusing DNA markers (analytical) with functional genetic elements (therapeutic/productive)
Memory Aid: STRs are for analysis and identification, not for causing biological changes