The GATE Grind

GATE 2024 BT – Question 23

Recombinant DNA Technology and Other Tools in Biotechnology · Molecular tools: PCR, DNA and RNA labelling, Sanger and next generation sequencing, Southern and northern blotting, in-situ hybridization, DNA fingerprinting · 1 mark · Multiple choice

Which one of the following is the basic principle of Sanger's DNA sequencing method?

  1. Chain termination by incorporation of dideoxynucleotides
  2. Chain elongation by incorporation of dideoxynucleotides
  3. Release of inorganic pyrophosphate
  4. Chain cleavage by modification of dideoxynucleotides

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Correct answer: (A) Chain termination by incorporation of dideoxynucleotides

Explanation

Dideoxynucleotides lack the 3'-OH, so once one is added the chain cannot be extended. Release of pyrophosphate is the basis of pyrosequencing.