What is the function of restriction endonuclease in recombinant DNA technology?

Restriction endonucleases, also known as restriction enzymes, play a crucial role in recombinant DNA technology by cutting DNA at specific recognition sites. These enzymes recognize particular sequences within the DNA and create double-strand breaks at those points. This ability to precisely cut DNA allows scientists to isolate specific genes or DNA fragments from different organisms.

When recombinant DNA technology is employed, the availability of restriction endonucleases enables researchers to combine DNA from different sources. By cutting the DNA of interest and the vector DNA (carrier DNA used for transferring the gene), compatible ends are generated that can facilitate the joining of these fragments. This process is foundational for cloning genes, constructing recombinant plasmids, and various applications in genetic engineering.

The other functions listed do not pertain to the role of restriction endonucleases. For instance, DNA replication is a separate process managed by DNA polymerase enzymes. Transcription involves converting DNA into mRNA and is carried out by RNA polymerase, while joining DNA fragments is a function performed by DNA ligase, which seals the nicks created by the restriction enzymes. Thus, the essential function of restriction endonucleases in recombinant DNA technology is accurately depicted by their ability to cut DNA at specific recognition sites.