Which type of bond forms the backbone of DNA by linking sugar to phosphate?

Which type of bond forms the backbone of DNA by linking sugar to phosphate?

• A. Hydrogen bonds
• B. Ionic bonds
• C. Covalent bonds
• D. Peptide bonds

Answer: (C)

The backbone of DNA is built from covalent phosphodiester bonds that join the sugar of one nucleotide to the phosphate of the next. Each linkage connects the 5' carbon of one deoxyribose to the 3' carbon of the next sugar, forming a continuous sugar–phosphate–sugar chain that runs 5' to 3'. These covalent bonds are strong and give the molecule its durable, repeating backbone. The bases themselves pair via hydrogen bonds in the interior of the double helix, not along the backbone. Ionic bonds aren’t the linking force here, and peptide bonds connect amino acids in proteins, not nucleotides.

The backbone of DNA is built from covalent phosphodiester bonds that join the sugar of one nucleotide to the phosphate of the next. Each linkage connects the 5' carbon of one deoxyribose to the 3' carbon of the next sugar, forming a continuous sugar–phosphate–sugar chain that runs 5' to 3'. These covalent bonds are strong and give the molecule its durable, repeating backbone. The bases themselves pair via hydrogen bonds in the interior of the double helix, not along the backbone. Ionic bonds aren’t the linking force here, and peptide bonds connect amino acids in proteins, not nucleotides.