when two dna pieces cut with the same restriction enzyme are combined, sticky ends will
Hence, if both vector DNA and donor DNA are cut with EcoRI, the sticky ends of the vector can bond to the sticky ends of a donor fragment when the two are mixed. Source(s): http://www.ncbi.nlm.nih.gov/books/bv.fcg... Sticky ends are when DNA is cleaved so that one strand of the DNA hangs over the other strand.