DNA is made up of chemical building blocks called nucleotides. Each nucleotide consists of three parts: a phosphate group, a sugar group called deoxyribose, and one of four nitrogen bases—adenine (A), thymine (T), cytosine (C), or guanine (G). These nucleotides link together in a chain with alternating phosphate and sugar groups, forming a sugar-phosphate backbone, and the nitrogen bases pair specifically (A with T and C with G) to form the "rungs" of a double helix structure. In summary, DNA is composed of:
- A sugar called deoxyribose
- A phosphate group
- Four nitrogen bases: adenine, thymine, cytosine, and guanine
The sequence of these bases encodes genetic information used for biological instructions in living organisms.
