A nitrogenous (nitrogen-containing) base is a nitrogen-containing molecule having the chemical properties of a base. It is an organic compound that owes its property as a base to the lone pair of electrons of a nitrogen atom. In biological sciences, nitrogenous bases are typically classified as the derivatives of two parent compounds, pyrimidine and purine.[1] They are non-polar and due to their aromaticity, planar. Both pyrimidines and purines resemble pyridine and are thus weak bases and relatively unreactive towards electrophilic aromatic substitution.[2] Their flat shape is particularly important when considering their roles in nucleic acids as nucleobases (building blocks of DNA and RNA): adenine, guanine, thymine, cytosine, and uracil. These nitrogenous bases hydrogen bond between opposing DNA strands to form the rungs of the "twisted ladder" or double helix of DNA or a biological catalyst that is found in the nucleotides. Adenine is always paired with thymine, and guanine is always paired with cytosine.
- ^ Nelson and Cox 2008, p. 272.
- ^ Carey 2006, p. 1206.
[edit] References
- Nelson, David L. and Michael M. Cox (2008). Principles of Biochemstry, ed. 5, W.H. Freeman and Company.
- Carey, Francis A. (2008). Organic Chemistry, ed. 6, Mc Graw Hill.
