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The colonies of recombinant bacteria appear white in contrast to blue colonies of non-recombinant bacteria because ofA. lnsertional inactivation of alphagalac- tosidase in recombinant bacteriaB. Inactivation of glycosidase enzyme in recombinant bacteriaC. Non-recombinant bacteria containing beta- galactosidaseD. insertional inactivation of alphagalac- tosidase in non-recombinant bacteria |
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Answer» Correct Answer - 3 In insertional inactivation a recombinant DNA is inserted within the coding sequence of enzyme J3 - galactosidase. If the plasmid in the bacteriadoes not have the insert (i.e., non - recombinants) then the chromogenic substrate gives blue coloured colonies. Presence of the insert (i.e., recombinants) leads to inactivation of the J3-galactosidase enzyme thus the colonies do not produce any colour. Option ( l) is wrong, it should be `beta` galactosidase Option (2) is wrong, it should be galactosidase instead of glycosidase Option (3) is correct, as the non- recombinants have the `beta` galactosidase enzymes intact. Option ( 4) is wrong it should be "Insertional inactivation of B galactosidase of recombinant bacteria". |
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