the backbone of the dna molecule is composed of sugars and
DNA also includes sugars and phosphate groups that make the phosphate-deoxyribose backbone. If you think of the structure of DNA as a twisted ladder, the rungs of the ladder are made from the nitrogenous bases.These bases pair up to make each step of the ladder. They also only pair up in a specific way.NA also includes sugars and phosphate groups that make the phosphate-deoxyribose backbone. If you think of the structure of DNA as a twisted ladder, the rungs of the ladder are made from the nitrogenous bases.