The building blocks of DNA are called nucleotides.
Nucleotides are composed of three components: a phosphate group, a sugar molecule (deoxyribose in the case of DNA), and a nitrogenous base. There are four types of nitrogenous bases in DNA: adenine (A), thymine (T), cytosine (C), and guanine (G). These bases pair specifically (A with T and C with G) to form the rungs of the DNA double helix.
Each nucleotide links to the next through the phosphate and sugar molecules, creating a long chain that makes up the DNA strand. This structure allows DNA to store and transmit genetic information in a precise and controlled manner, which is essential for the functioning of all living organisms.