Question

Which structural component of DNA is hydrophilic and located on the exterior of the double helix?

Options

• Deoxyribose sugars

• Nitrogenous bases

• Sugar-phosphate backbone

• Hydrogen bonds

Answer 1

The sugar-phosphate backbone, which is hydrophilic (water-loving), is positioned on the exterior surface of the DNA double helix. The nitrogenous bases, which are hydrophobic, stack flat on the interior of the helix. This arrangement allows the hydrophilic backbone to interact with the aqueous cellular environment while maintaining the stability of the hydrophobic base stacking interactions inside.