guanineArticle Free Pass guanine, an organic compound belonging
to the purine group, a class of compounds with a characteristic
two-ringed structure, composed of carbon and nitrogen atoms, and
occurring free or combined in such diverse natural sources as
guano (the accumulated excrement and dead bodies of birds, bats,
and seals), sugar beets, yeast, and fish scales. It is a
component of nucleic acids, the cell constituents that store and
transmit hereditary traits. Guanine was first discovered in
guano in 1846 and was isolated in 1891 from nucleic acids from
which it is readily prepared. More complex compounds obtainable
from nucleic acids include the nucleosides guanosine and
deoxyguanosine, in which guanine is combined with the sugars
ribose and deoxyribose and the nucleotides guanylic acid and
deoxyguanylic acid, which are phosphoric acid esters of
guanosine and deoxyguanosine. Nucleotides are molecules that
constitute the fundamental structural units of nucleic acids;
nucleosides are smaller subunits lack