nucleic acid (nu-kle´ik, -kla´ik)
A family of macromolecules, of molecular masses ranging upward from 25,000, found in the chromosomes, nucleoli, mitochondria, and cytoplasm of all cells, and in viruses; in complexes with proteins, they are called nucleoproteins. On hydrolysis they yield purines, pyrimidines, phosphoric acid, and a pentose, either d-ribose or d-deoxyribose; from the last, the n.a.'s derive their more specific names, ribonucleic acid and deoxyribonucleic acid. N.a.'s are linear (i.e., unbranched) chains of nucleotides in which the 5´-phosphoric group of each one is esterified with the 3´-hydroxyl of the adjoining nucleotide.
infectious n.a. viral n.a. that can infect cells and bring about the production of viruses.
1. A compound yielding a hydrogen ion in a polar solvent (e.g., in water); a.'s form salts by replacing all or part of the ionizable hydrogen with an electropositive element or radical. 2. In popular language, any chemical compound that has a sour taste (given by the hydrogen ion). 3. Sour; sharp to the taste. 4. Relating to a.; giving an a. reaction. For individual acids, see specific names. [L. acidus, sour]
bile a.'s steroid a.'s found in bile; e.g., taurocholic and glycocholic a.'s, used when biliary secretion is inadequate and for biliary colic. Their physiological roles include fat emulsification. Their synthesis is reduced in disorders of the peroxisomes.
Broonsted a. an a. that is a proton donor.
conjugate a. the protonated compound of two compounds that differ in structure only by the presence of the labile proton.
dibasic a. an a. containing two ionizable atoms of hydrogen in the molecule. See acid (1).
fatty a. See fatty acid.
inorganic a. an a. made up of molecules not containing organic radicals; e.g., HCl, H2SO4, H3PO4.
Lewis a. an a. that is an electron pair acceptor.
monobasic a. an a. containing one ionizable atom of hydrogen in the molecule. See acid (1).
organic a. an a. made up of molecules containing organic radicals; e.g., acetic a., citric a., which contain the ionizable -COOH group.
polybasic a. an a. containing more than three ionizable atoms of hydrogen in the molecule. See acid (1).
ruberythric acid (ru-ber´e-thrik) a glycoside of alizarin and a disaccharide containing d-xylose and d-glucose residues found in the roots of the madder plant.
wax a. a long-chain monocarboxylic a. with an even number of carbons, often found esterified in waxes (e.g., lauric acid).
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