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Match Group-I (selection agent) and Group-II (gene) in CORRECT combination.

Group-IGroup-II
P. KanamycinI. pmi
Q. HygromycinII. bar
R. PhosphinothricinIII. nptII
S. MannoseIV. ptxD
V. dhfr
VI. hpt

  • A.P-III, Q-VI, R-II, S-I
  • B.P-IV, Q-III, R-II, S-I
  • C.P-I, Q-VI, R-III, S-II
  • D.P-II, Q-I, R-V, S-VI

Answer: A

The correct combination is P-III, Q-VI, R-II, S-I.

  • Kanamycin is detoxified by neomycin phosphotransferase II, encoded by nptII (III).
  • Hygromycin B is inactivated by hygromycin phosphotransferase, hpt (VI).
  • Phosphinothricin (glufosinate) is acetylated and inactivated by phosphinothricin acetyltransferase, encoded by bar (II).
  • Mannose is used for positive selection: cells carrying phosphomannose isomerase, pmi (I), can convert mannose-6-phosphate to fructose-6-phosphate and grow on it.

The extra genes are distractors: ptxD (phosphite dehydrogenase) is used with phosphite, and dhfr (dihydrofolate reductase) with methotrexate. Options B, C and D each pair at least one agent with one of these or with the wrong gene.

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