During DNA replication, the specific chemical reaction that occurs is the formation of phosphodiester bonds between nucleotides to synthesize a new complementary DNA strand. This process is catalyzed by enzymes called DNA polymerases. The overall reaction can be summarized as follows: Nucleotide n + dNTP Nucleotide n+1 + PPiwhere Nucleotide n represents the growing DNA chain, dNTP is the deoxynucleoside triphosphate that will be added to the chain, and PPi is the released pyrophosphate.The DNA replication process begins with the unwinding of the double-stranded DNA by helicase enzymes, which creates a replication fork. Single-stranded binding proteins SSBs stabilize the separated strands. The enzyme primase synthesizes a short RNA primer to provide a starting point for DNA polymerase. DNA polymerase then adds complementary nucleotides to the template strand, synthesizing the new DNA strand in the 5' to 3' direction.To ensure that errors in the DNA sequence are corrected during replication, cells have a proofreading mechanism. DNA polymerases have a 3' to 5' exonuclease activity, which allows them to remove incorrectly paired nucleotides. When an incorrect nucleotide is incorporated, DNA polymerase detects the mismatch, reverses its direction, and removes the incorrect nucleotide using its exonuclease activity. After the incorrect nucleotide is removed, DNA polymerase resumes the synthesis of the new strand in the 5' to 3' direction.In addition to the proofreading activity of DNA polymerases, cells also have other DNA repair mechanisms, such as mismatch repair, base excision repair, and nucleotide excision repair, which can correct errors that escape the proofreading process. These repair mechanisms help maintain the integrity and accuracy of the genetic information during DNA replication.