What are the building blocks or subunits that compose the DNA molecule?

• A. Sugars
• B. Nucleotides
• C. Amino acids
• D. Nucleosides

Answer: (B)

DNA is built from repeating units called nucleotides. Each nucleotide includes a deoxyribose sugar, a phosphate group, and a nitrogenous base. These nucleotides link together via phosphodiester bonds to form the long DNA backbone, with the bases projecting inward and pairing across strands (A pairs with T, G pairs with C). The sequence of bases encodes genetic information. Nucleosides (sugar plus base) lack the phosphate and aren’t the complete subunit, sugars are only part of a nucleotide, and amino acids form proteins, not DNA. So the subunits that compose DNA are nucleotides.