Which component forms the backbone of DNA?

Which component forms the backbone of DNA?

• A. The sugar-phosphate backbone forms the DNA polymer's structural framework.
• B. The nitrogenous bases pair to form the backbone.
• C. Lipids compose the backbone of DNA.
• D. Amino acids stabilize DNA through ionic bonds.

Answer: (A)

DNA's backbone is the sugar-phosphate chain. Each nucleotide contributes a deoxyribose sugar and a phosphate group, and covalent phosphodiester bonds link the sugar of one nucleotide to the phosphate of the next. This repeating sugar–phosphate framework runs along the length of the molecule, providing the structural support, with the nitrogenous bases sticking out to pair with the opposite strand. The genetic information is stored in the sequence of those bases, not in the backbone. Lipids form membranes, and amino acids form proteins, so they do not constitute the DNA backbone.

DNA's backbone is the sugar-phosphate chain. Each nucleotide contributes a deoxyribose sugar and a phosphate group, and covalent phosphodiester bonds link the sugar of one nucleotide to the phosphate of the next. This repeating sugar–phosphate framework runs along the length of the molecule, providing the structural support, with the nitrogenous bases sticking out to pair with the opposite strand. The genetic information is stored in the sequence of those bases, not in the backbone. Lipids form membranes, and amino acids form proteins, so they do not constitute the DNA backbone.