in contrast , if bamhi-cleaved ptkb8 dna was cotransformed into cells along with a circular dna molecule containing a tk gene deleted only at its 3 ' end or only at its 5 ' end ( mp10tk delta 3 ' or mp10tk delta 5 ' ) , then the efficiency of recombination could be more than 4 orders of magnitude higher than it was with circular mp10tk delta 3 ' delta 5 ' dna .
C0012854
dna
C0012925
circular