Which of the following is a function of a restriction endonuclease?

A restriction endonuclease is an enzyme that plays a critical role in molecular biology by cutting DNA at specific sequences. The function of cutting DNA in the interior of the molecule is essential for various applications, such as genetic engineering and cloning.

Restriction endonucleases recognize specific nucleotide sequences and create breaks within the DNA strand, which allows researchers to isolate genes of interest, create recombinant DNA, or perform other manipulations necessary for genetic studies. This characteristic makes them invaluable tools in biotechnology, where precise DNA modification is required.

While some enzymes indeed perform other functions, such as stabilizing unwound strands during replication or catalyzing the addition of new nucleotides, these are not roles performed by restriction endonucleases. Their primary and defining function is the precise cutting of DNA within the sequence, leading to various downstream applications in genetic research and biotechnology.