noun, plural: nitrogenous bases
Each nucleic acid is comprised of a series of nucleotides. The nucleotide, in turn, is made up of phosphoric acid, sugar (5-carbon), and nitrogenous base. The nitrogenous bases are one of the fundamental components of nucleic acids, such as DNA. They may also form nucleosides wherein the nitrogenous base is attached to a sugar. Nucleic acids such as DNA and RNA molecules contain the genetic information that are important for all cellular functions and heredity.
The nitrogenous bases occur in two major forms: purines and pyrimidines. While both purines and pyrimidines are heterocyclic aromatic compounds, they can be differed from each other based on the chemical structure. The purines occur as two carbon rings whereas the pyrimidines occur as one carbon ring. The purine has a pyrimidine ring fused to an imidazole ring. The pyrimidine has only a pyrimidine ring. Thus, the purine has four nitrogen atoms whereas the pyrimidine has two.
The nitrogenous bases of purines are adenine and guanine whereas the nitrogenous bases of pyrimidines are cytosine, thymine, and uracil. These five nitrogenous bases are regarded as primary or canonical since they are the fundamental units of the genetic code. The nitrogenous components are one of the major distinctions used to distinguish DNA from RNA molecules. In DNA, thymine complementary pairs with adenine whereas in RNA, uracil matches with adenine. The thymine differs from uracil in having a methyl group, which the uracil lacks.
- nitrogen base