If DNA was to be a ladder, the supporting side rails would be the sugar-phosphate molecules.
The DNA is a double-stranded molecule in which the two strands are associated with weak hydrogen bonds.
The two strands also twist around one another to form a double helix structure.
The backbone of the helix is the sugar-phosphate molecule while the rungs of the ladder are the nucleotide base-pairing between the two strands.
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