Briefly describe the principle of DNA fingerprinting using Variable Number Tandem Repeats (VNTRs) and how it can be applied to establish identity between individuals.
Answer
VNTR loci consist of short DNA sequences repeated a variable number of times; PCR amplifies these regions, and gel electrophoresis separates the fragments, producing a band pattern unique to each individual, which can be compared to confirm identity.
Step-by-step solution
- Define VNTRs as DNA segments where a short motif is repeated in tandem, with the number of repeats differing among individuals.
- Explain that primers flanking a VNTR locus are used in PCR to amplify the region from genomic DNA.
- State that the amplified products are separated by agarose gel electrophoresis, where fragment length reflects the number of repeats.
- Describe that the resulting banding pattern (DNA fingerprint) is compared between samples; matching patterns indicate the same individual or close relatives, while differences confirm distinct identities.
Common mistake: Confusing VNTRs with single nucleotide polymorphisms (SNPs)
Concept tested: DNA fingerprinting using VNTRs
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