An autoradiogram of DNA fingerprints has four lanes, each with bands numbered from the well downwards. The crime-scene sample has bands at positions 2, 5, 7 and 9. Suspect S1 has bands at 1, 5, 8 and 9; suspect S2 at 2, 5, 7 and 9; and suspect S3 at 2, 4, 7 and 10. The probe used binds a VNTR. Which conclusion is correct?
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A VNTR is a minisatellite whose copy number varies from person to person, so the size and pattern of bands differ between individuals. Only S2 shows exactly the same pattern as the crime-scene sample.
- A.
S1 shares only bands 5 and 9; a match needs every band to agree.
- C.
Sharing two bands is not a match; bands 4 and 10 do not appear in the sample.
- D.
VNTR copy number differs between individuals, which is why fingerprints differ.
NCERT: Class 12 Biology, Chapter 5, 5.10