The GATE Grind

GATE 2019 BT – Question 41

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 · 2 marks · Multiple choice

Which factors affect DNA-polymerase fidelity in PCR? P Mg²⁺ concentration; Q pH; R annealing temperature.

  1. P and Q only
  2. P and R only
  3. Q and R only
  4. P, Q and R

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Show answer and explanation

Correct answer: (A) P and Q only

Explanation

Magnesium concentration influences nucleotide selection and catalytic interactions; pH changes ionization and enzyme chemistry, so P and Q affect polymerase fidelity. Annealing temperature principally controls primer hybridization specificity rather than the nucleotide-incorporation fidelity asked for here. Under that distinction the keyed choice is A.

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