What type of bond is found between all components of the DNA molecule except the nitrogen bases?

• A. Hydrogen bonds
• B. Ionic bonds
• C. Covalent bonds
• D. Peptide bonds

Answer: (C)

DNA’s structure is built from nucleotides joined into long polymers. The sugar–phosphate backbone is connected by covalent phosphodiester bonds, which form a strong, continuous chain along each strand. Between the two strands, the nitrogenous bases pair via hydrogen bonds, which are weaker and sit between strands rather than forming the backbone. While the sugar–base linkage (glycosidic bond) is also covalent, the phrase “except the nitrogen bases” focuses on the backbone connections, which are covalent. Ionic bonds aren’t the main stabilizing links in DNA, and peptide bonds occur in proteins, not DNA. So the bonds that connect the components of the DNA molecule, aside from the bases, are covalent.