Biotechnology: Principles and Processes · Class 12 · CBSE · Science Biology
A foreign DNA fragment is inserted into the tetracycline-resistance gene of the plasmid pBR322, while the ampicillin-resistance gene remains function…
Practice question from Biotechnology: Principles and Processes (Class 12 · CBSE · Science Biology), with the correct answer and a step-by-step solution.
hard · MCQ · Q-AF5C32
A foreign DNA fragment is inserted into the tetracycline-resistance gene of the plasmid pBR322, while the ampicillin-resistance gene remains functional. After transformation, which colony phenotype identifies recombinant bacteria?
- A.Growth on tetracycline but no growth on ampicillin
- B.Growth on ampicillin but no growth on tetracyclineCorrect answer
- C.No growth on either ampicillin or tetracycline
- D.Growth on both ampicillin and tetracycline
Solution
Insertion of foreign DNA disrupts the tetracycline-resistance gene, causing insertional inactivation. The intact ampicillin-resistance gene allows growth on ampicillin, so recombinants are ampicillin-resistant but tetracycline-sensitive.
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