Nucleotides and DNA/RNA backbone polarity
Bases carry sequence information on a chemically directional sugar–phosphate backbone.
Key knowledge
A nucleotide contains a base, a pentose sugar and one or more phosphate groups. DNA uses deoxyribose, with hydrogen at sugar carbon 2′; RNA uses ribose, with a 2′ hydroxyl. Their usual bases are A, G and C with T in DNA and U in RNA. In ordinary DNA/RNA chains, 3′–5′ phosphodiester linkages connect sugars through phosphate, giving backbone directionality. The two strands of the usual DNA double helix are antiparallel; RNA can also fold by internal base pairing.
Conditions and scope
- Canonical backbone and common bases; modified bases and other nucleic-acid chemistries also exist.
- Sugar–phosphate covalent linkage and base-pair hydrogen bonding are different interactions; RNA is not required to remain an unstructured single strand.
Sources · 2
References
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Evidence and review
Nucleotide components, ribose/deoxyribose distinction and chemical directionality of the common DNA/RNA backbones.
2026-10-10 · Independent Mathematics and Information editor (AI editorial/source review; not the Chemistry/Biology/Earth author). The specified introductory inventory has no unresolved demonstrated material gap after the changes and body-based reuse. Existing advanced references retain their historical scoped approvals. English-only reference prose and explicit Lithuanian-translation-pending status are preserved.
Foundational review
2026-10-10 · Independent AI editorial inspection of this new compact reference entry, its equations, applicability, sources and knowledge connections.
Sources from other places
Agreement within this scope
Base/sugar/phosphate composition, 3′–5′ links and antiparallel DNA.
DNA and RNA differ in sugar chemistry and usual pyrimidine bases.
NCERT
- Biology XII: Molecular Basis of Inheritance IndiaEnglish
§5.1.1, printed pp80–82: DNA/RNA backbone and base pairing; §5.4, printed pp88–90: semiconservative replication; §5.5.2–5.5.3, printed pp92–95: transcription and RNA products; §5.7, printed pp98–100: translation and activated amino acids
- Biology XII: Molecular Basis of Inheritance
Entry details
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- foundation-bio-nucleotide-backbone
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- foundations-audit.1
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