Practice question

EcoRI recognizes GAATTC and creates a staggered cut between G and A on both strands, leaving AATT 5' overhangs that are single-stranded and complementary, termed sticky or cohesive ends. DNase I is a nonspecific endonuclease that degrades DNA randomly. Taq and Pfu polymerases are thermostable DNA synthesizers used in PCR, not restriction enzymes, and they add non-templated A or produce blunt products respectively. Therefore only EcoRI among listed creates characteristic cohesive termini useful for directional cloning and efficient ligation via complementary base pairing.