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The colonies of recombinant bacteria appear white in contrast to blue colonies of non-recombinant bacteria because of:

  1. A
    Non-recombinant bacteria containing beta-galactosidase.
  2. B
    Insertional inactivation of alpha-galactosidase in non-recombinant bacteria.
  3. C
    Insertional inactivation of beta-galactosidase in recombinant bacteria.
  4. D
    Inactivation of glycosidase enzyme in recombinant bacteria.

Solution & Step-by-step Explanation

In blue-white screening, the recombinant DNA is inserted into the coding sequence of the -galactosidase gene (). This insertional inactivation prevents the enzyme from being produced. Thus, these bacteria cannot break down X-gal (a chromogenic substrate) and remain white.

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The colonies of recombinant bacteria appear white in contrast to blue colonies of non-recombinant bacteria because of:
A
Non-recombinant bacteria containing beta-galactosidase.
B
Insertional inactivation of alpha-galactosidase in non-recombinant bacteria.
C
Insertional inactivation of beta-galactosidase in recombinant bacteria.
D
Inactivation of glycosidase enzyme in recombinant bacteria.

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