In recombinant DNA technology , specific restriction endonucleases are used that will isolate a particular gene and cleave the sugar phosphate backbones at different points ( retaining symmetry ) .
The double - stranded restriction fragments have single - stranded ends .
In recombinant DNA technology , specific restriction endonucleases are used that will isolate a particular gene and cleave the sugar phosphate backbones at different points ( retaining symmetry ) , so that the double - stranded restriction fragments have single - stranded ends .