Q.29 Gene expression can not be analyzed using this technique
DNA fingerprinting cannot be used to analyze gene expression. It generates DNA band patterns from minisatellites/VNTRs via PCR or Southern blotting for identification purposes (forensics, paternity), measuring DNA quantity/presence rather than mRNA levels or transcriptional activity.
Option Analysis
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(1) DNA fingerprinting: Not for gene expression—detects genetic variation (STRs, SNPs), not RNA abundance; static genomic profile.
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(2) Fluorescence in situ hybridization (FISH): Detects specific mRNA transcripts via fluorescent probes; single-cell gene expression localization.
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(3) RT-PCR: Gold standard—reverse transcribes mRNA to cDNA, quantifies via qPCR (Ct values); measures expression levels precisely.
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(4) DNA microarray: Hybridizes labeled cDNA to genome-wide probes; relative expression ratios via fluorescence intensity.
Answer: (1) DNA fingerprinting.
Introduction to Gene Expression Analysis
Gene expression cannot be analyzed using DNA fingerprinting because it profiles static genomic DNA polymorphisms, not dynamic mRNA levels. True expression techniques (RT-PCR, microarray, FISH) target RNA transcripts to quantify transcription under different conditions.
Technique Comparison Matrix
| Technique | Target | Measures | Expression? |
|---|---|---|---|
| DNA fingerprinting | Genomic DNA | VNTR/STR length | No |
| FISH | mRNA/DNA | Spatial localization | Yes |
| RT-PCR | cDNA (from mRNA) | Transcript abundance | Yes |
| Microarray | cDNA | Genome-wide expression | Yes |
Why DNA Fingerprinting Fails for Expression
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Static: Same multilocus pattern regardless of cell state
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DNA-based: Ignores RNA processing (splicing, degradation)
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Qualitative: Band presence/absence, not quantitative levels
GATE Molecular Biology Strategy
Key distinction: DNA fingerprinting = identity/genotyping; RT-PCR/microarray = expression profiling. Tests understanding of nucleic acid targets and purpose.
