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STD 12 - 5. molecular basis of inheritance — NEET STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceNEETSTD 12 - 5. molecular basis of inheritance4 Marks
MCQ
What is it that forms the basis of $DNA$ fingerprinting ?
  • A
    The relative proportions of purines and pyrimidines in $DNA$
  • B
    The relative difference in the $DNA$ occurrence in blood, skin and saliva.
  • C
    The relative amount of $DNA$ in the ridges and grooves of the fingerprints.
  • ✓
    Satellite $DNA$ occurring as highly repeated short $DNA$ segments.
✓

Answer

Correct option: D.
Satellite $DNA$ occurring as highly repeated short $DNA$ segments.
d
(d) : $DNA$ fingerprinting is a technique of determining nucleotide sequences of certain areas of $DNA$ which are unique to each individual. The difference of about $0.1\%$ or $3 × 10^6$ base pairs (out of $3 × 10^9\ bp$) provides individuality to each human being. Human genome possesses numerous small noncoding but inheritable sequences of bases which are repeated many times. These sequences occur near telomere, centromeres, $Y$ chromosome and heterochromatic area. The area with same sequence of bases repeated several times is called repetitive $DNA$. It is separated as satellite from the bulk $DNA$ during density gradient centrifugation and hence called satellite $DNA$ where, repetition of bases is in tandem. Satellite $DNAs$ show polymorphism (the occurrence of mutations in a population at high frequency), which is the basis of genetic mapping of human genome as well as $DNA$ fingerprinting. While mutations in genes produce alleles with different expressions, mutations in noncoding repetitive $DNA$ have no immediate impact. These mutations which have piled up with time form the basis of polymorphism.

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