If a restriction enzyme is used to digest both a closed circular DNA molecule and a linear DNA molecule with six recognition sites, how many fragments will be generated in total?

13

Restriction endonucleases are enzymes that play a crucial role in recombinant DNA techniques by cutting DNA at specific recognition sites. Linear DNA found in the eukaryotic nucleus has two free ends, while circular DNA is predominant in prokaryotes, mitochondria, chloroplasts, and plasmids. The restriction endonuclease will cleave the DNA at the recognition site, resulting in the generation of DNA fragments.

Linear DNA with two free ends will produce 7 fragments, and circular DNA will produce 6 fragments.

Therefore, the total number of fragments generated from both linear and circular DNA molecules with the same restriction enzyme having six recognition sites is 13.