Phosphodiester bonds connect adjacent nucleotides by linking which components?

• A. Bond linking two amino acids
• B. Bond linking base pairs in DNA
• C. Phosphate group of one nucleotide to the sugar of the next
• D. Bond linking lipid molecules

Answer: (C)

Nucleotides in DNA and RNA are linked by phosphodiester bonds that form the sugar–phosphate backbone. Each nucleotide contributes a sugar and a phosphate, and the bond forms between the phosphate group of one nucleotide and the sugar of the next, creating a continuous chain. This linkage gives the molecule its directional backbone, running from 5' to 3'. The hydrogen bonds between bases then stabilize any double-stranded structure, but the actual connection along the strand is the phosphodiester bond between phosphate and sugar. Other types of bonds, like peptide bonds between amino acids or lipid connections, do not join nucleotides in the backbone.