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Which nitrogenous bases are found in DNA?

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Diagram of a DNA polynucleotide chain showing linked deoxyribose sugars, phosphate groups, and nitrogenous bases (adenine, guanine, cytosine, thymine), with an inset comparing ribose and uracil in RNA. — Nucleic acid A portion of the polynucleotide chain of deoxyribonucleic acid (DNA), with an inset showing the corresponding pentose sugar and pyrimidine base in ribonucleic acid (RNA).

DNA contains four nitrogenous bases: two purines, adenine (A) and guanine (G), and two pyrimidines, cytosine (C) and thymine (T).312

While uracil (U) is also a nitrogenous base found in nucleic acids, it is specific to RNA and replaces thymine in that molecule. Within the DNA structure, these bases form complementary pairs, where adenine always bonds with thymine and cytosine always bonds with guanine.341