You cut some sheep DNA and some plasmid DNA with the same restriction enzyme.The plasmid contains an AmpR 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