!!! Overview
[{$pagename}] are organic molecules that serve as the monomer units for forming the nucleic acid polymers [Deoxyribonucleic Acid] ([DNA]) and [Ribonucleic Acid] ([RNA]), both of which are essential biomolecules within all life-forms on Earth. 


[{$pagename}] are the building blocks of nucleic acids; they are composed of three subunit molecules: 
* a nitrogenous base (also known as nucleobase or ACGT)
** adenine (A)
** thymine (T)
** guanine (G)
** uracil (U)
** cytosine (C). 
* a five-carbon sugar (ribose or deoxyribose)
* at least one phosphate group.


The nitrogenous bases form hydrogen bonds 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 [{$pagename}]s. 

[{$pagename}] base pairs:
* Adenine (A) is always paired with thymine (T)
* Guanine (G) is always paired with cytosine (C). 
Adenine (A) forms two hydrogen bonds with thymine in [DNA] and two hydrogen bonds with uracil in [RNA], while three hydrogen bonds are formed between guanine and cytosine. There are a variety of other non-canonical base pairs that occur in nature due to the versatility of these molecular structures.

Uracil is only present in [RNA], replacing thymine. 

Pyrimidines include thymine, cytosine, and uracil. They have a single ring structure. 

Purines include adenine and guanine. They have a double ring structure.

!! More Information
There might be more information for this subject on one of the following:
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* [#1] - [Nucleotide|Wikipedia:Nucleotide|target='_blank'] - based on information obtained 2019-09-01