EcoRI recognizes the palindrome sequence GAATTC and breaks the phosphodiester bonds between the G and A (G*A) on both strands. Draw a diagram to demonstrate what the sticky-ends would look like.
5'-G A A TTC-3'
3'-C T T AAG-5'
After EcoRI digestion, the resulting sticky ends would be:
5'-G AATTC-3'
3'-CTTAA G-5'
Note the overhangs on both strands, indicated by the single-stranded regions at the end of each strand. These can base-pair with complementary overhangs on other fragments with the same Sticky end sequences.
To demonstrate what the sticky ends would look like, let's start with the palindrome sequence GAATTC:
Original DNA sequence:
5' - GAATTC - 3'
3' - CTTAAG - 5'
When EcoRI recognizes and cuts this sequence, it breaks the phosphodiester bonds between the G and A on both strands. The result would be two cut ends with overhanging nucleotide sequences, called sticky ends:
Cut DNA sequence:
5' - G AATTC - 3'
3' - CTTAA G - 5'
Here's a diagram to illustrate the sticky ends:
Original DNA strand:
5' - GAATTC - 3'
3' - CTTAAG - 5'
After cutting with EcoRI, you have two strands with sticky ends:
Strand 1:
5' - G - 3'
3' - C - 5'
Strand 2:
5' - AATTC - 3'
3' - TTAAG - 5'
Note that the sticky end of Strand 1 is the complementary nucleotide sequence to the sticky end of Strand 2, allowing them to anneal and rejoin during DNA ligation.