Each nucleotide consists of a heterocyclic base linked via a five-carbon sugar (deoxyribose or ribose) to a phosphate group. DNA and RNA each contain four different bases. The purines adenine (A) and guanine (G) and the pyrimidine cytosine (C) are present in both DNA and RNA. So both DNA and RNA have four nitrogenous bases each—three of which they share (Cytosine, Adenine, and Guanine) and one that differs between the two (RNA has Uracil while DNA has Thymine). One of the most significant similarities between DNA and RNA is that they both have a phosphate backbone to which the bases attach.
