Figure 18.2 Cutting, Splicing, and Joining DNA Some restriction enzymes (EcoRI is shown here) make staggered cuts in DNA. EcoRI can be used to cut two different DNA molecules (blue and orange). The exposed bases can hydrogen-bond with complementary exposed bases on other DNA fragments, forming recombinant DNA. DNA ligase stabilizes the recombinant molecule by forming covalent bonds in the DNA backbone.