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A nucleic acid is a complex, high-molecular-weight biochemical macromolecule composed of nucleotide chains that convey genetic information. The most common nucleic acids are deoxyribonucleic acid ( DNA) and ribonucleic acid ( RNA). Nucleic acids are found in all living cells and viruses.
Highly simplified diagram of a double-stranded nucleic acid. Yellow circles represent phosphate; green 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 pyrimidinePyrimidine is an organic compound, a conjugated amine which is similar to benzene, but with a heterocyclic ring: two nitrogen atoms taking the place of carbon atoms at positions 1 and 3 relative to each other around the six-member ring. Three bases of the), a pentoseA pentose is a monosaccharide with five carbon atoms. Both ribose and deoxyribose are pentoses . List of aldopentoses ribose arabinose xylose lyxose List of ketopentoses ribulose xylulose See also triose, tetrose, hexose monosaccharide, disaccharide Monos sugarThis article deals with sugar as food and as an important, widely traded commodity; the word also has other uses; see Sugar (disambiguation A sugar is a form of carbohydrate; the most commonly used sugar is a white crystalline solid, sucrose; used to alte, and a phosphateIn chemistry, a phosphate is a polyatomic ion or radical consisting of one phosphorus atom and four oxygen. In the ionic form, it carries a -3 formal charge, and is denoted PO3-. In a biochemical setting, a free phosphate ion in solution is called inorgan group. Different nucleic acid types differ in the specific sugar found in their chain (e.g. DNA or deoxyribonucleic acid contains 2- deoxyriboseDeoxyribose (more fully 2-deoxyribose is a five- carbon sugar (a pentose) derived from the pentose sugar ribose by the repacement of the hydroxyl group at the 2 position with hydrogen, leading to the net loss of an oxygen. Ribose forms a five member rings). Also, the nitrogenous bases possible in the two nucleic acids are different: adenineAdenine is one of the two purine bases used in forming nucleotides of the nucleic acids DNA and RNA. In DNA, adenine (A) binds to thymine (T) to assist in stabilizing the nucleic acid structures. In RNA, adenine binds to uracil (U). Adenine forms adenosin, cytosineCytosine is one of the 5 main nitrogenous bases used in storing and transporting genetic information within a cell. It is a pyrimidine derivative, with a heterocyclic aromatic ring and two substituents attached (an amine group at position 4 and a keto gro, and guanineGuanine (2- amino-6- oxy purine) is one of the four main nitrogenous bases found in nucleic acids (e. DNA and RNA). Guanine is a purine derivative and in Watson-Crick base pairing forms hydrogen bonds with cytosine. The nucleoside is called guanosine. are possible in both RNA and DNA, while thymine is possible only in DNA and uracil is possible only in RNA.
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 extend 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 usually single-stranded, but any given strand is likely to fold back upon itself to form double-helical regions. DNA is usually double-stranded, though some viruses have single-stranded DNA as their genome.
Nucleic acids are primarily biology's means of storing and transmitting genetic information, though RNA is also capable of acting as an enzyme.
