nitrogenbas

Nitrogenbas is a nonstandard term sometimes used to refer to nitrogenous bases, the nitrogen-containing components of nucleic acids that encode genetic information. The bases are divided into two major classes: purines, which include adenine (A) and guanine (G); and pyrimidines, which include cytosine (C), thymine (T) in DNA, and uracil (U) in RNA. These molecules are built on aromatic ring systems and are the sites of hydrogen-bonding interactions that enable base pairing.

In DNA, A pairs with T (two hydrogen bonds) and C pairs with G (three hydrogen bonds). In RNA, thymine is replaced by uracil, so A pairs with U. Bases are covalently linked to sugar moieties to form nucleotides, which polymerize to create DNA and RNA backbones while the bases project inward to read genetic information.

The sequence of nitrogen bases constitutes genetic information, read by cellular machinery to synthesize proteins according to the genetic code. Base modifications, such as cytosine methylation, influence gene expression and genome stability. Bases also participate in enzymatic recognition during replication, transcription, and repair.

The concept of base pairing and the role of nitrogen bases were clarified in the mid-20th century, with Chargaff's rules guiding Watson and Crick's double helix model in 1953. Related topics include nucleotides, nucleic acids, base pairing, purines, and pyrimidines.