Final answer:
Restriction enzymes are used as molecular scissors in genetic engineering due to their ability to cut specific DNA sequences, facilitating the creation of recombinant DNA.
Step-by-step explanation:
The molecules used as molecular scissors in genetic engineering are restriction enzymes. These enzymes function to cleave specific DNA sequences and are vital in the creation of recombinant DNA. Restriction enzymes recognize specific DNA sequences, typically palindromic, and cut the DNA at these sites. This enables scientists to splice together DNA from different organisms, which is a foundational technique in biotechnology and genetic engineering. Notable among these enzymes are Type-II restriction endonucleases like EcoRI, which cuts at the sequence 5' GAATTC 3'.