Which statement correctly describes the DNA backbone?

Which statement correctly describes the DNA backbone?

• A. Bases pairing with hydrogen bonds
• B. Lipids and proteins
• C. Sugar and phosphate molecules connected by phosphodiester bonds
• D. Amino acids linking by peptide bonds

Answer: (C)

DNA's backbone is the repeating sugar-phosphate chain formed by phosphodiester bonds. Each nucleotide contributes a deoxyribose sugar and a phosphate group; these components are linked covalently from the 5' phosphate of one sugar to the 3' hydroxyl of the next, creating the continuous backbone along the strand. The nitrogenous bases extend from the sugar units and pair with complementary bases on the opposite strand through hydrogen bonds, which stabilizes the double helix but does not comprise the backbone itself. Therefore, the description of sugar and phosphate molecules connected by phosphodiester bonds correctly describes the DNA backbone. The other statements describe base pairing, lipids and proteins, or peptide bonds in proteins, which are not part of the backbone.

DNA's backbone is the repeating sugar-phosphate chain formed by phosphodiester bonds. Each nucleotide contributes a deoxyribose sugar and a phosphate group; these components are linked covalently from the 5' phosphate of one sugar to the 3' hydroxyl of the next, creating the continuous backbone along the strand. The nitrogenous bases extend from the sugar units and pair with complementary bases on the opposite strand through hydrogen bonds, which stabilizes the double helix but does not comprise the backbone itself. Therefore, the description of sugar and phosphate molecules connected by phosphodiester bonds correctly describes the DNA backbone. The other statements describe base pairing, lipids and proteins, or peptide bonds in proteins, which are not part of the backbone.