Which parts of a nucleotide contribute to the DNA backbone?

Which parts of a nucleotide contribute to the DNA backbone?

• A. Nitrogenous base
• B. Sugar
• C. Sugar and phosphate
• D. Phosphate

Answer: (C)

The backbone of DNA is the sugar–phosphate chain that gives the molecule its sturdy, repeating framework. Each nucleotide contributes a sugar (deoxyribose) and a phosphate group, and these two components are linked by phosphodiester bonds to form alternating sugar and phosphate units along the strand. The nitrogenous bases sit on the 1' carbon of the sugar and extend inward to pair with the opposite strand; they do not form part of the backbone themselves. So the parts that make up the DNA backbone are the sugar and phosphate groups.

The backbone of DNA is the sugar–phosphate chain that gives the molecule its sturdy, repeating framework. Each nucleotide contributes a sugar (deoxyribose) and a phosphate group, and these two components are linked by phosphodiester bonds to form alternating sugar and phosphate units along the strand. The nitrogenous bases sit on the 1' carbon of the sugar and extend inward to pair with the opposite strand; they do not form part of the backbone themselves. So the parts that make up the DNA backbone are the sugar and phosphate groups.