Question

How many fragments will be generated in total upon digestion of a closed circular DNA molecule and liner DNA molecule with a same restriction enzyme having six recognition sites on both DNA molecules?

• A. $13$
• B. $14$
• C. $12$
• D. $6$

Answer 1

The correct option is A $13$

Restriction endonucleases are a class of enzymes that cut the DNA by recognising a specific sequence or base pairing of the DNA.

These enzymes have a very important role in recombinant DNA techniques.

Linear DNA is the form of DNA present in the eukaryotic nucleus and is composed of two free ends. Circular DNA is predominantly found in prokaryotes, whereas the mitochondria, chloroplast and plasmids also contain circular DNA. Circular DNA is found in the cytoplasm of the prokaryotic cell, in mitochondria or in the chloroplast.

So when the restriction endonuclease will cut the DNA from the recognition site fragments of DNA will be produced. As the linear NA has 2 free ends it will produce 7 fragments and the circular DNA will produce 6 fragments.

So, the correct option is '13'.