Which component differentiates a nucleotide from a nucleoside?

Which component differentiates a nucleotide from a nucleoside?

• A. A nitrogenous base
• B. A sugar
• C. A phosphate group
• D. A ring structure

Answer: (C)

The key difference is the phosphate group. A nucleoside is just a sugar (ribose or deoxyribose) bound to a nitrogenous base. When a phosphate group is added to the sugar, forming one or more phosphate units, you obtain a nucleotide. Those phosphate groups enable the nucleotides to link together via phosphodiester bonds, creating the backbone of DNA or RNA and enabling energy transfer in molecules like ATP. The sugar and the ring structure, and the nitrogenous base, are present in both nucleosides and nucleotides, so they don’t differentiate them.

The key difference is the phosphate group. A nucleoside is just a sugar (ribose or deoxyribose) bound to a nitrogenous base. When a phosphate group is added to the sugar, forming one or more phosphate units, you obtain a nucleotide. Those phosphate groups enable the nucleotides to link together via phosphodiester bonds, creating the backbone of DNA or RNA and enabling energy transfer in molecules like ATP. The sugar and the ring structure, and the nitrogenous base, are present in both nucleosides and nucleotides, so they don’t differentiate them.