The recognition sequence is Palindromic where the sequence of base pairs reads the same on both the DNA strands when the orientation of reading is kept the same i.e. 5' -3' or 3' -5' direction e.g. 5'-GAATTC-3' 3'-CTTAAG-5'. Restriction enzymes cut the strand a little away from the centre of the palindrome sites, but between the same two bases on the opposite strands. This leaves single-stranded overhanging stretches at the ends. They are called sticky ends.
