A series of phosphodiester bonds create which structure?

• A. Nucleotides
• B. Sugar-phosphate backbone
• C. Double helix
• D. Phospholipid bilayer

Answer: (B)

Phosphodiester bonds form the backbone of a nucleic acid. Each bond links the sugar of one nucleotide to the phosphate of the next, creating a repeating sugar-phosphate chain that runs along the length of the molecule. This sugar-phosphate backbone provides the structural framework and directionality (5' to 3') for the strand, while the nitrogenous bases extend from this backbone and carry the genetic information.

The two strands of DNA form a double helix because of base pairing between the two backbones, but the backbone itself is the continuous chain created by those phosphodiester linkages. Nucleotides are the building blocks that make up the polymer, not the entire structure by themselves, and a phospholipid bilayer relates to membranes, not nucleic acids.