Which part forms the backbone of the DNA double helix?

Which part forms the backbone of the DNA double helix?

• A. Nitrogenous base pairs
• B. Sugar-phosphate backbone
• C. Hydrogen bonds between bases
• D. Lipid layers

Answer: (B)

The backbone of the DNA double helix is the sugar-phosphate chain that forms the structural framework of the molecule. It consists of alternating deoxyribose sugars and phosphate groups linked by phosphodiester bonds, giving DNA its directionality and stability. The nitrogenous bases extend inward and pair across the two strands to form the rungs of the ladder, but those base pairs are not part of the backbone. Hydrogen bonds between the paired bases help hold the two strands together, yet they don’t constitute the backbone itself. Lipid layers have no role in the DNA’s double-helix structure. So, the sugar-phosphate backbone is what provides the backbone.

The backbone of the DNA double helix is the sugar-phosphate chain that forms the structural framework of the molecule. It consists of alternating deoxyribose sugars and phosphate groups linked by phosphodiester bonds, giving DNA its directionality and stability. The nitrogenous bases extend inward and pair across the two strands to form the rungs of the ladder, but those base pairs are not part of the backbone. Hydrogen bonds between the paired bases help hold the two strands together, yet they don’t constitute the backbone itself. Lipid layers have no role in the DNA’s double-helix structure. So, the sugar-phosphate backbone is what provides the backbone.