The double helix of DNA in the B-form is stabilized by:
A) covalent bonds between the 3' end of one strand and the 5' end of the other.
B) hydrogen bonding between the phosphate groups of two side-by-side strands.
C) hydrogen bonds between the riboses of each strand.
D) nonspecific base-stacking interaction between two adjacent bases in the same strand.
E) ribose interactions with the planar base pairs.

Question

Quizplus · Accepted Answer

The double helix of DNA in the B-form is stabilized by nonspecific base-stacking interaction between two adjacent bases in the same strand. This stacking interaction is driven by the hydrophobic effect and results in the stacking of the flat, planar aromatic rings of nucleotide bases on top of each other, creating a stable helical structure. Hydrogen bonds between complementary base pairs in opposite strands also contribute to the stability of the double helix, but they are not the primary stabilizing force. Covalent bonds between the 3' end of one strand and the 5' end of the other (phosphodiester bonds) hold the nucleotides within each strand together but do not contribute to the overall helical structure. Hydrogen bonding between the phosphate groups of two side-by-side strands and ribose interactions with the planar base pairs are not mechanisms that stabilize the double helix.

The Double Helix of DNA in the B-Form Is Stabilized