How do the structures of RNA and DNA differ? Only RNA, and not DNA, has a primary structure. Adenine pairs with thymine in DNA, while adenine pairs with uracil in RNA. DNA contains the sugar ribose, while RNA contains the sugar deoxyribose. The sugar-phosphate backbone of DNA is formed by phosphodiester linkages, while the sugar-phosphate backbone of RNA is formed by peptide bonds. Guanine pairs with cytosine in DNA, while guanine pairs with adenine in RNA.