What is DNA primarily composed of?

What is DNA primarily composed of?

• A. Amino acids forming a chain
• B. Nucleotides forming a double helix
• C. Carbohydrates arranged in rings
• D. Fatty acids forming a strand

Answer: (B)

DNA’s basic unit is the nucleotide, and its two long strands wind together into a double helix. Each nucleotide has a sugar, a phosphate group, and a nitrogenous base, and many nucleotides link to form the backbone while complementary bases pair across the strands to hold them together. This nucleotide-based, double-helix structure is what DNA is primarily composed of. The other options point to different biomolecules—proteins built from amino acids, carbohydrates formed from rings of sugars, and fats built from fatty acids—so they don’t describe DNA’s main components.

DNA’s basic unit is the nucleotide, and its two long strands wind together into a double helix. Each nucleotide has a sugar, a phosphate group, and a nitrogenous base, and many nucleotides link to form the backbone while complementary bases pair across the strands to hold them together. This nucleotide-based, double-helix structure is what DNA is primarily composed of. The other options point to different biomolecules—proteins built from amino acids, carbohydrates formed from rings of sugars, and fats built from fatty acids—so they don’t describe DNA’s main components.