You cut some sheep DNA and some plasmid DNA with the same restriction enzyme.The plasmid contains an Amp^R gene and a lacZ gene.You mix together the fragments of sheep DNA and the linearized plasmid.You transform bacteria with your mixture,and plate the bacterial cells on growth media containing the antiobiotic ampicillin and X-gal (the substrate of beta-galactosidase).You need to pick the bacterial colonies that contain recombinant plasmids.Which colonies do you choose? A)only the blue colonies - these contain recombinant plasmids B)only the white colonies - these contain recombinant plasmids C)the largest colonies - these are the most resistant to ampicillin and thus more likely to contain a recombinant plasmids D)all colonies will contain plasmids,but additional testing is needed to determine if the plasmids are recombinant E)all surviving colonies;if they grow on the media they are ampicillin-resistant and contain recombinant plasmids

Question

Quizplus · Accepted Answer

The white colonies indicate that the lacZ gene has been disrupted by the insertion of sheep DNA, thus they contain recombinant plasmids. Blue colonies indicate that the lacZ gene is intact and functional, suggesting no insertion has occurred in that gene.

You Cut Some Sheep DNA and Some Plasmid DNA with the Same