Let’s fade away the base pairs to study the spiraling backbones.
These consist of repeating units of a sugar and a phosphate group (PO4).
The sugar, known as 2-deoxyribose, is based on a five-member ring with one oxygen atom and four carbons. The bases in DNA's core attach to one of the carbon atoms of this ring. (And it is from this sugar that DNA derives its full name of deoxyribonucleic acid).
This model uses chemists’ standard color coding for atoms: Carbon = black; Hydrogen = white; Oxygen = red; Nitrogen = blue. We also use purple to represent phosphorus (a color chemists use to represent a variety of atoms).
