A plasmid has two antibiotic restriction genes..?
A plasmid has two antibiotic restriction genes, one for ampicillin and one for tetracycline. It is treated with a restriction enzyme that cuts in the middle of the ampicillin gene. DNA fragments containing a human globin gene were cut with the same enzyme. The plasmids and fragments are mixed, treated with ligase, and used to transform bacteria cells. Clones that have taken up the recombinant DNA are ones that:
A. are blue and can grow on plates with both antibiotics
B. can grow on plates with ampicilin but not with tetracycline
C. can grow on plates with tetracycline but not with ampicillin
D. cannot grow with any antibiotics
E. can grow on plates with tetracycline and are blue.
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Since the RE cuts are in the middle of the ampicillin resistance gene, any insert placed there will destroy the ampicillin resistance. Since it hasn't destroyed the tetracyclin resistance, that will remain.
There is no mention anywhere of the lacZ gene that makes colonies blue in the presence of X-gal, so none of the colonies should be blue.
So - the answer is C.
You disrupted the amp gene with an insertion and left the tet gene alone. Both of those genes are antibiotic resistance genes and have nothing to do with blue color (that would be due to a beta-galactosidase enzyme expressed from the plasmid and you didn't mention that as part of the plasmid). So, since the amp resistance gene doesn't work and the tet resistance gene does work, what answer looks the best?