​Cytosine
Definition
Cytosine (C) is one of the four nucleotide bases in DNA, with the other three being adenine (A), guanine (G) and thymine (T). Within a double-stranded DNA molecule, cytosine bases on one strand pair with guanine bases on the opposite strand. The sequence of the four nucleotide bases encodes DNA’s information.
Narration
Cytosine. The fact that DNA encodes all of its information in four bases, each with its own letter, allows us to write the DNA code by just representing the letters.