Biomolecules

Polynucleotide strands wind in to a right handed double helix.

Sugar-phosphate back bone lies at in side and bases lie out side of helix.

Double helix is stabilized by hydrogen bonding formed in two strands.

$\mathrm{A}=\mathrm{T}$ and $\mathrm{G}=\mathrm{C}$ are complementary base pairs.