If a recombinant DNA bearing gene for resistance to antibiotic ampicillin is transferred to E.coli cells, the host cells become transformed into ampicillin-resistant cells. If such bacteria are transferred on agar plates containing ampicillin, only transformants will grow and the non-transformed recipient cells will die. The ampicillin-resistant gene in this case is called as _______________.

Selectable marker

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Recombinant protein

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Cloning site

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Chemical scalpels

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Solution

The correct option is A Selectable marker
The cloning vector requires the presence of a selectable marker, which helps in identifying and eliminating non-transformants and selectively permitting the growth of the transformants. Normally, the genes encoding resistance to antibiotics such as ampicillin, chloramphenicol, tetracycline or kanamycin, etc. are considered useful selectable markers for E. coli. The normal E.coli cells do not carry resistance against any of these antibiotics.

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