The sides of the DNA ladder molecule are made up of alternating sugar and phosphate groups.

* Sugar: The sugar in DNA is deoxyribose, a five-carbon sugar.

* Phosphate: The phosphate group is a negatively charged molecule that links the sugars together.

These sugar-phosphate groups form the backbone of the DNA molecule, creating a strong and stable structure. The bases (adenine, guanine, cytosine, and thymine) attach to the sugars, forming the "rungs" of the ladder.