DAT Molecular Genetics Practice Test 2026 – Comprehensive Exam Prep

DNA's backbone is formed by covalent phosphodiester bonds that link the sugar of one nucleotide to the phosphate of the next, creating the continuous sugar–phosphate chain that runs 5' to 3'. This linkage connects adjacent nucleotides and provides the structural framework for the molecule, while the bases project outward to pair with their complementary partners on the opposite strand. Hydrogen bonds, by contrast, stabilize base pairing between strands rather than linking nucleotides along the backbone. Peptide bonds connect amino acids in proteins, and ionic interactions are not the bonds that form the DNA backbone.