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Nucleic acid

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noun, plural: nucleic acids

Any of the group of complex compounds consisting of linear chains of monomeric nucleotides whereby each monomeric unit is composed of phosphoric acid, sugar and nitrogenous base, and involved in the preservation, replication, and expression of hereditary information in every living cell


A nucleic acid is a biopolymer composed of monomeric units of nucleotides. Each nucleotide that makes up a nucleic acid is comprised of phosphoric acid, sugar (5-carbon), and nitrogenous base. The chains of nucleotides in a nucleic acid are linked by 3', 5' phosphodiester linkages.

Nucleic acids may be in the form of DNA or RNA molecules containing the genetic information important for all cellular functions and heredity.

DNA is a double-stranded nucleic acid containing the genetic information of a living thing. It is essential for the cell growth, division, and function of an organism. It is composed of two strands that twist together to form a helix. Each strand consists of alternating phosphate (PO4) and pentose sugar (2-deoxyribose), and attached on the sugar is a nitrogenous base, which can be adenine, thymine, guanine, or cytosine. In DNA, these bases pair; adenine pairs with thymine and guanine with cytosine. Hence, DNA is a ladder-like helical structure.

RNA is a molecule consisting of a long linear chain of nucleotides. Each nucleotide unit is comprised of a sugar, phosphate group and a nitrogenous base. It differs from a DNA molecule in a way that the sugar backbone is a ribose (deoxyribose in DNA) and the bases are adenine, guanine, cytosine and uracil (thymine in DNA). In some viruses, RNA is the genetic material whereas for most organisms, RNAs are involved in protein synthesis, post-transcriptional modification or DNA replication, and gene regulation.

Word origin: nucleic (of the nucleus) + acid.

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