Question

Base stacking interactions in the DNA double helix are primarily of what nature?

Options

• Ionic interactions

• Hydrophobic interactions

• Covalent bonds

• Hydrogen bonds

Answer 1

Base stacking interactions are hydrophobic in nature, occurring between the flat aromatic rings of adjacent base pairs stacked vertically within the helix interior. These interactions contribute additional stability to the double helix beyond the hydrogen bonds between complementary bases. The hydrophobic stacking of bases is one reason the nitrogenous bases are positioned in the interior of the helix rather than on the exterior with the hydrophilic backbone.