Question

Which of the following statements is untrue about restriction enzymes?

पर्याय

• They are made by bacteria and viruses.

• The first one was isolated in 1970, and thereafter hundreds of different ones have been isolated and purified.

• They produce single-stranded complementary ends that can join together two different DNA strands.

• Each enzyme cuts DNA at a different specific base sequence.

Answer 1

They are made by bacteria and viruses.

Explanation:

Restriction enzymes are actually made by bacteria (not viruses) as a defence mechanism against viruses. The first restriction enzyme was isolated in 1970, and since then hundreds have been isolated. They cut DNA at specific base sequences and produce single-stranded complementary (sticky) ends that can join two different DNA strands. Each enzyme cuts DNA at a specific site, making them useful molecular scissors in genetic engineering.