What is the primary function of restriction enzymes?

The primary function of restriction enzymes is to cut DNA at specific sequences. These enzymes, which are often referred to as "molecular scissors," recognize specific short sequences of nucleotides within the DNA and cleave the DNA at those sites, leading to the formation of smaller DNA fragments. This cutting action is essential for various molecular biology applications, including cloning, genetic engineering, and the analysis of DNA.

Restriction enzymes are derived from bacterial cells, where they serve as a defense mechanism against invading viruses by cutting the viral DNA, thus preventing infection. This specificity for particular sequences allows scientists to manipulate DNA precisely, making them invaluable tools for genetic research and biotechnology.

The other options represent different biological processes: synthesizing RNA from DNA refers to transcription; replicating DNA pertains to DNA polymerase activity during cell division; and repairing DNA mutations involves various repair mechanisms, such as nucleotide excision repair. While these processes are critical in genetics, they do not describe the main role of restriction enzymes.