Figure Q10-14 shows the recognition sequences and sites of cleavage for the restriction enzymes Sal I, Xho I, Pst I, and Sma I and a plasmid with the sites of cleavage for these enzymes marked.
A. After which of the following treatments described in choices 1 through 5 can the plasmid shown in Figure Q10-14 be recircularized simply by treating with DNA ligase? Assume that after treatment any small pieces of DNA are removed, and it is the larger portion of plasmid only that you are trying to recircularize.
After digestion with
1. Sal I alone.
2. Sal I and Xho I.
3. Sal I and Pst I.
4. Sal I and Sma I.
5. Sma I and Pst I.
B. In which of the cases 1–5 can the plasmid be recircularized by adding DNA ligase after the cut DNA has been treated with DNA polymerase in a mixture containing the four deoxynucleotides? Again assume that you are trying to recircularize the larger portion of plasmid.