The restriction endonuclease EcoRI cleaves the DNA sequence 5'-GAATTC-3' in such a way as to leave a 5' overhang, which is often referred to as a "sticky end". To 5' overhang with the complementary sequence this sticky end adhere.
The palindrome EcoRI restriction site breaks DNA after G and creates sticky ends with AATT. G/corresponding AATTC's DNA sequence is CTTAA/G, where "/" designates the location of the peptide bond break.
When the ssDNA sequence 5'-GAATTC'-3 is recognised by the restriction endonuclease EcoRI, a single-strand cut is made between the G and A nucleotides.
At the ultimate end of double-stranded DNA, an overhang is single-stranded DNA. This can occur on either strand, and if it does, there will either be a 5' overhang on the 5' end of the strand or a 3' overhang on the 3' end of the strand.
