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Nucleic acid

The nucleic acids, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), are one of the basic classes of macromolecules studied in biochemistry.


Highly simplified diagram of a double-stranded nucleic acid. Green circles represent phosphate; yellow circles represent pentose; red circles represent nitrogenous bases. Solid lines represent covalent bonds; dashed lines represent hydrogen bonds.

Nucleic acid, so called because of its prevalence in cellular nuclei, is the generic name of family of biopolymers. The monomers are called nucleotides, and each consists of three components: a nitrogenous heterocyclic base (either a purine or a pyrimidine), a pentose sugar, and a phosphate group. Different nucleic acid types differ in the specific sugar found in their chain (e.g. DNA or deoxyribonucleic acid contains 2'-deoxyriboses).

The sugars and phosphates in nucleic acids are connected to each other in an alternating chain through shared oxygens (forming a phosphodiester functional group). Using the conventional nomenclature, the carbons to which the phosphate groups are attached are the 3' and the 5' carbons. The bases are pendant from a glycosidic linkage to the 1' carbon of the pentose ring.

Nucleic acids may be single-stranded or double-stranded. A double-stranded nucleic acid consists of two single-stranded nucleic acids hydrogen-bonded together. RNA is always single-stranded, and DNA is usually double-stranded, though some viruses have single-stranded DNA.

Nucleic acids are primarily biology's means of storing and transmitting genetic information, though RNA is also capable of acting as an enzyme.

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