The correct answer is option (4) as
EcoRI does not cut the DNA with blunt ends. Instead, it cuts the DNA with sticky / cohesive / staggered ends on each strand.
EcoRI is a restriction endonuclease that recognises a specific palindromic sequence and cuts at a specific site within the DNA, known as the restriction site. It is not an exonuclease as exonucleases remove nucleotides from the free ends of the DNA.
The recognition sequence for
EcoRI is
| 5′−G↓−A−A−T−T−C−3′ |
| 3′−C−T−T−A−A↑−G−5′ |
and it cuts the DNA between bases
G and
A only when the sequence GAATTC is present in the DNA.
Therefore, 'A' and '
E ' represent incorrect features about EcoRI, whereas 'B', '
C ' and '
D ' are correct features of EcoRI.
The other options, i.e., (1), (2) and (3) are incorrect as they represent incorrect combinations of features w.r.t. EcoRI.