Question

Which of the following statements is untrue about restriction enzymes

• A. They are made by bacteria and viruses
• B. The first one was isolated in 1970, and thereafter hundreds of different ones have been isolated and purified
• C. They produce single-stranded complementary ends that can join together two different DNA strands
• D. Each enzyme cuts DNA at a different specific base sequence

Answer 1

The correct option is A They are made by bacteria and viruses

Restriction enzymes cut DNA strands by identifying specific sequences of nucleotides. They are made by only bacteria, not viruses. In the bacterial cell, restriction enzymes cleave foreign DNA, thus eliminating infecting organisms.

So, the correct option is 'They are made by bacteria and viruses'.