Question

Assertion :When the DNA sequences of two people are cut using the same restriction enzyme, the length and number of fragments obtained are different for both. Reason: DNA sequence is arranged tandemly in many copy numbers which varies from chromosome to chromosome in an individual, showing high degree of polymorphism.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Both Assertion and Reason are incorrect

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

In satellite DNA, repetition of bases is in tandem. Depending upon length, base composition and numbers of tandemly repetitive units, satellite DNAs have subcategories like microsatellites and minisatellites. Satellite DNAs show polymorphism. The mutations in the noncoding sequences have piled up with time and form the basis of DNA polymorphism (variation at genetic level arises due to mutations) DNA polymorphism is the basis of genetic mapping of human genome as well as DNA fingerprinting. DNA of each organism has specific sequences that can be cleaved by restriction enzymes to produce fragments of different lengths. These fragments are called restriction fragments. The occurrence of different length of DNA sequence cleaved at restriction sites is referred to as restriction fragment length polymorphism (RFLP).

So, the correct answer is 'Both Assertion and Reason are correct and Reason is the correct explanation for Assertion'.