Question

A researcher inserts a DNA segment at the BamHI recognition site within a plasmid; this site is located within the tetracycline resistance gene. This plasmid also has a gene for ampicillin resistance. Following DNA transformation, the researcher must differentiate the bacteria that have taken up the recombinant DNA from those that have taken up either the DNA segment only or have taken up intact plasmids. In order to do so, the researcher should select the bacteria that

1) show resistance to tetracycline
2) show resistance to ampicillin
3) do not show resistance to tetracycline
4) do not show resistance to ampicillin

Answer 1

To differentiate between bacteria that have taken up recombinant DNA and those that have taken up DNA segment only or intact plasmids, the researcher should select the bacteria that show resistance to tetracycline and ampicillin.

Step-by-step explanation:

To differentiate the bacteria that have taken up the recombinant DNA from those that have taken up either the DNA segment only or have taken up intact plasmids, the researcher should select the bacteria that show resistance to tetracycline and resistance to ampicillin. This is because the plasmid used in the experiment contains genes for both tetracycline resistance and ampicillin resistance. So, the bacteria that have taken up the recombinant DNA will exhibit resistance to both antibiotics.