The sides of DNA molecules are made up of alternating sugar (deoxyribose) and phosphate groups. These form the backbone of the DNA molecule, while the rungs are made up of nitrogenous bases (adenine, guanine, cytosine, and thymine).

Here's a breakdown:

* Sides: Sugar-phosphate backbone

* Rungs: Nitrogenous bases (A-T, G-C)

So, the answer is sugar (deoxyribose) and phosphate groups.