dNMP, or deoxyribonucleoside monophosphate, is a building block of DNA. It consists of a deoxyribose sugar, a nitrogenous base (adenine, guanine, cytosine, or thymine), and a phosphate group. The nitrogenous base determines the specific nucleotide, and these nucleotides are paired with their complementary counterpart to form the rungs of the DNA ladder.
Initiation: DNA replication begins at specific locations in the genome called origins of replication. Proteins bind to these origins and unwind the DNA to create a replication fork.
Primer Synthesis: An RNA primer is synthesized by primase. This primer provides a starting point for DNA synthesis.
Elongation: DNA polymerase enzymes add dNTPs to the growing DNA strand. The enzyme reads the template strand and incorporates the complementary dNTP. For example, if the template strand has an adenine (A), the polymerase will add a thymine (T) dNTP to the new strand.
Formation of Phosphodiester Bonds: When a dNTP is added to the growing DNA strand, it loses two of its three phosphate groups (as pyrophosphate), and a phosphodiester bond is formed between the 3' hydroxyl group of the last nucleotide in the chain and the 5' phosphate group of the incoming dNTP.
Proofreading: DNA polymerases have proofreading activity that checks and corrects any mismatched bases to ensure high fidelity in DNA replication.
Termination: Once the entire DNA molecule has been replicated, the process concludes, and the replication machinery disassembles.