Question

From which of the following the restriction enzymes were originally isolated?

• A. Viruses, which use them to cut bacterial DNA
• B. Bacteria, which use them to cut viral DNA
• C. Viruses, which use them to turn off their host bacterial DNA
• D. Protists, which use them to organize themselves into colonial life-forms
• E. Injured tissue, where they restrict the movement of molecules across the plasma membrane

Answer 1

The correct option is B Bacteria, which use them to cut viral DNA

Restriction enzymes are isolated from the bacteria that manufactures them also. They protect the bacteria from the attacking virus (bacteriophage). Restriction enzyme cuts the DNA of bacteriophage at specific sites before it kills the host cell.