Draw the hydrogen bonds between the bases. The letter R represents the rest of the nucleotide. The bases are positioned approximately as they would be in a DNA double helix. To indicate a hydrogen bond, simply draw a regular single bond between the atoms. Be careful not to modify the existing atoms or bonds in any way, nor add extraneous atoms or bonds. Draw the hydrogen bond(s) between thymine and adenine. Draw the hydrogen bond(s) between guanine and cytosine.