Question

Which of the following is the example of chemical scissors?

• A. EcoRI
• B. HindIII
• C. BamHI
• D. All of the above

Answer 1

The correct option is D All of the above

Restriction endonucleases are the enzymes that recognise specific sequences in the DNA and cut the DNA into fragments. The specific sites are 4-6 bp long and are called as restriction sites. Since these enzymes cut the DNA molecules into small fragments, they are also known as chemical/molecular scissors. They differ from regular scissors as they do not cut the DNA at random sites rather they recognise the specific DNA sequences for which they have complementary "teeth" just like a jigsaw puzzle pieces. EcoRI is restriction endonuclease enzyme present in E. coli as a part of the restriction modification system. The nucleic acid sequence of its restriction site is 5' GAATTC 3'. HindIII is type I restriction enzyme isolated from Haemophilus influenzae. It cuts the DNA at (5') AAGCTT (3'). BamHI is a type II restriction endonuclease isolated from Bacillus amyloliquefaciens. It recognizes short sequences of DNA (5' GGATCC 3') and specifically cleaves DNA at this site. Since, all these enzymes have specific restriction sites, they are chemical scissors.

So, the correct answer is option D.