Nucleotides have three major parts: a five-carbon sugar, a phosphate group, and a nitrogen-containing base. The sugar is either a ribose, forming RNA or a deoxyribose making DNA. The nitrogen containing base can be in the form a single or double carbon ring structure. The single carbon ring structures, known as the pyrimidines, have three forms: cytosine and thymine, which are found in DNA, and uracil which is found only in RNA. The double carbon ring structures, known as the purines, have two forms: guanine, and adenine.

The four different types of DNA nucleotides are then linked together, forming a large double-stranded molecule. Each strand's backbone consists of joined sugars and phospate groups of the adjacent nucleotides. The nucleotides are then connected to form a double-stranded molecule that twists helically, like a spiral staircase.

The DNA molecule is the carrier of all genetic material within the cell. It has a very basic structure in which large amounts of information can be stored by a simple arrangement of nucleotides.