Several scientists wish to cut the DNA representing the normal human gene that makes insulin from a human chromosome. They wish to place it into a bacterial plasmid. The bacteria will then use this human gene to synthesize insulin cheaply, and in large amounts.

A bacterial plasmid (circular DNA) was cleaved with a restriction enzyme leaving the following DNA:

Which insulin gene DNA can be used as a donor in making recombinant DNA?

The answer is C. The AT at the left of the donor DNA matches the TA code at left of the plasmid. The TA at right of the donor DNA matches the AT of the plasmid.