Guanine

=Guanine=

**Guanine **  (often abbreviated to **G ** , chemical formula C5H5N5O) is a nitrogenous nucleobase, one of the four commonly found in DNA. When forming part of a deoxynucleotide, the compound is called **deoxyguanosine monophosphate **  (dGMP), and it is attached to a growing DNA chain by addition of a **deoxyguanosine triphosphate ** (dGTP) precursor. It may also be found in RNA where its monomeric constituent is called simply **guanosine monophosphate ** (GMP) from a **<span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">guanosine triphosphate ** <span style="font-family: Arial,Helvetica,sans-serif; font-size: 12.6px;"> (GTP) precursor.

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 12.6px;"> Guanine is a purine derivative, and it base-pairs with cytosine using three hydrogen bonds.