What is the primary function of endonucleases?

Endonucleases are enzymes that play a crucial role in DNA repair and modification by cleaving the phosphodiester bonds within a DNA strand. This allows them to remove damaged or mispaired sections of DNA, which is essential for maintaining the integrity of genetic information. They act by recognizing specific sites within the DNA where the damage has occurred and then making cuts in the DNA strand, enabling the subsequent repair processes to occur.

In DNA repair mechanisms, such as base excision repair or nucleotide excision repair, endonucleases remove the damaged or erroneous segments, which are then filled in and sealed by other enzymes, ensuring that the DNA is accurately restored. This ability to cleave DNA makes endonucleases vital for cellular processes involved in maintaining genomic stability.

The other options represent functions carried out by different types of enzymes or processes. For instance, RNA primers are synthesized by primase during DNA replication, and transcribing DNA into RNA is primarily facilitated by RNA polymerase. The bonding of nucleotides is typically a function attributed to DNA polymerases during replication and repair processes.