Concept 1 / 9
DNA Building Blocks: Nucleotides
DNA is a double-stranded helix of two antiparallel and complementary strands. The repeating subunit is the nucleotide.
Hierarchy of components:
BASE + SUGAR = NUCLEOSIDE
BASE + SUGAR + PHOSPHATE = NUCLEOTIDE| Part | Detail |
|---|---|
| Sugar | Pentose (5-carbon). DNA = β-D-2-deoxyribose (H at 2'); RNA = β-D-ribose (OH at 2') |
| Phosphate | Forms the sugar–phosphate backbone, gives extra stability |
| Base | A, T, C, G (DNA); A, U, C, G (RNA) |
The sugar carbons are numbered 1'–5'. The single difference between ribose and deoxyribose is the 2'-OH (ribose) vs 2'-H (deoxyribose) — this is literally "the D in DNA."