The GATE Grind

GATE 2026 BT – Question 18

Plant, Animal and Microbial Biotechnology · Animals: Hybridoma technology, stem cells, animal cloning, transgenic, knock-out and knock-in animals · 1 mark · Multiple choice

For monoclonal antibody production, hypoxanthine ____________.

  1. allows DNA synthesis in the absence of de novo dTMP synthesis
  2. allows purine synthesis in cells containing HGPRT
  3. induces cell fusion
  4. prevents de novo nucleotide synthesis

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Correct answer: (B) allows purine synthesis in cells containing HGPRT

Explanation

HAT medium has hypoxanthine, aminopterin and thymidine. Aminopterin blocks the de novo synthesis. Hypoxanthine feeds the salvage pathway for purines, which works only in cells with HGPRT (the hybridomas), and thymidine allows dTMP synthesis.