Biochemistry 4th Edition by Christopher Mathews,Kensal van Holde, Dean Appling, Spencer Anthony Cahill

Exercise 4

pBR322 DNA (4.32 kb) was cleaved with Hindlll nuclease and lig-ated to a Hindlll digest of human mitochondrial DNA. One recombinant plasmid DNA was analyzed by gel electrophoresis of restriction cleavage fragments, with the following results: lane A = Eco RI-treated recombinant, lane B = Hin dIII-treated vector, and lane C = Hin dIII-treated recombinant.
(a) Why was the recombinant plasmid treated with Eco RI for determination of its size
(b) How might you explain the discrepancy between the size of the recombinant molecule and the sum of the sizes of the Hindlll cleavage fragments
(c) Draw a diagram of the recombinant showing the locations of the Hindlll cleavage sites.