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🔬 Biology  ·  Biotechnology: Principles and Processes  ·  NEET

Selection of recombinants by insertional inactivation of antibiotic markers is cumbersome. An alternative uses a gene coding for an enzyme that, when intact, cleaves a chromogenic substrate. This selection works because:

Answer: Recombinant colonies do not produce colour.

  • A Recombinant colonies produce a coloured product
  • B Non-recombinant colonies fail to grow
  • C Recombinant colonies do not produce colour
  • D Both colony types appear identical

Correct answer: C. Recombinant colonies do not produce colour

Explanation: If the insert interrupts the enzyme-coding sequence, the enzyme is not produced, so recombinant colonies do not develop colour, while non-recombinants produce a coloured product.

PlasmidGene of interestcutrestriction enzymeligateRecombinantplasmidHost cell

Recombinant DNA technology: a gene of interest and plasmid are cut by the same restriction enzyme, ligated into a recombinant plasmid, and introduced into a host cell.

Concept context

Recombinant DNA, GMOs, PCR, CRISPR, and biotechnology applications. Growing importance in NEET.

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