Question

Which of the following shows a double-stranded segment of DNA that might be cut by a restriction enzyme? 5’ GACTGACT 3’ 3’ CTGACTGA 5’ 5’ GAGGAG 3’ 3’ CTCCTC 5’ 5’ GAATTC 3’ 3’ CTTAAG 5’

Answer 1

Restriction enzymes recognize and bind to specific sequences of DNA. When it finds its target sequence, a restriction enzyme will make a double-stranded cut in the DNA molecule. As an example of how a restriction enzyme recognizes and cuts at a DNA sequence, let's consider EcoRI, a common restriction enzyme used in labs. EcoRI cuts at the following site:
5'-GAATTC-3'
3'-CTTAAG-5'

So the double-stranded segment of DNA 5’ GAATTC-3' would be cut by the restriction enzyme.