Guanine

DNA is comprised of four bases, these are guanine (G), adenine (A), cytosine (C) and thymine (T). Guanine, a derivative of purine, consists of a planar, fused pyrimidine-imidazole ring and has the chemical formula C₅H₅N₅O. The bases exist in complementary pairs with guanine hybridising to cytosine by three hydrogen bonds, contributing to the stability of the DNA molecule^[1].

References

1. ↑ New World Encyclopedia Authors. (2008) New World Encyclopedia. Available at: http://www.newworldencyclopedia.org/entry/Guanine (Accessed: 20th October 2015)