tetrad


tetrad
1. A collection of four things having something in common such as a deformity with four features, e.g., Fallot tetralogy. SYN: tetralogy. 2. In chemistry, a quadrivalent element. 3. In heredity, a bivalent chromosome that divides into four chromatids during meiosis. [G. tetras (t.-), the number four]
- Fallot t. SYN: tetralogy of Fallot.

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tet·rad 'te-.trad n a group or arrangement of four: as
a) a tetravalent element, atom, or radical
b) a group of four cells arranged usu. in the form of a tetrahedron and produced by the successive divisions of a mother cell <a \tetrad of spores>
c) a group of four synapsed chromatids that become visibly evident in the pachytene stage of meiotic prophase and are produced by the longitudinal splitting of each of two paired homologous chromosomes

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1. the four cells resulting from meiosis after the second telophase.
2. the four chromatids of a pair of homologous chromosomes (see bivalent) in the first stage of meiosis.

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tet·rad (tetґrad) [Gr. tetra- four] a group of four similar or related entities, as (1) any element or radical having a valence, or combining power, of four; (2) a group of four homologous chromatids formed in the pachytene state of the first meiotic prophase; (3) a square of cells produced by the division into two planes of certain cocci (Sarcina).

Medical dictionary. 2011.

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  • Tetrad — may refer to:* Tetrad (chromosomal formation), a chromosomal formation in meiosis * Tetrad (general relativity), a mathematical frame of reference in general relativity * Tetrad (genetics), the four spores of a yeast * Tetrad (Greek philosophy),… …   Wikipedia

  • Tetrad — Tet rad, n. [L. tetras, adis, Gr. ?, ?: cf. F. t[ e]trade.] 1. The number four; a collection of four things; a quaternion. [1913 Webster] 2. (Chem.) A tetravalent or quadrivalent atom or radical; as, carbon is a tetrad. [1913 Webster] …   The Collaborative International Dictionary of English

  • Tetrad — war eine britische Rockband aus dem südenglischen Bournemouth, Grafschaft Dorset, die 1968 gegründet wurde und aus der Palmer James Band hervorging. Biographie Der Gitarrist und Sänger Richard Palmer James, der Bassist und Sänger John Wetton und… …   Deutsch Wikipedia

  • tetrad — (n.) 1650s, from Gk. tetras (comb. form tetrad ) group of four (see TETRA (Cf. tetra )) …   Etymology dictionary

  • tetrad — tetrad. См. тетрада. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • tetrad — tetrád, tetráde, s.n. (înv.) caiet. Trimis de blaurb, 09.03.2007. Sursa: DAR …   Dicționar Român

  • tetrad — [te′trad΄] n. [Gr tetras (gen. tetrados), four: see TETRA ] 1. a group or set of four 2. Bot. a group of four cells formed by division within a spore mother cell during meiosis 3. Chem. an atom, radical, or element that is tetravalent 4. Genetics …   English World dictionary

  • tetrad — noun Etymology: Greek tetrad , tetras, from tetra Date: 1653 a group or arrangement of four: as a. a group of four cells produced by the successive divisions of a mother cell < a tetrad of spores > b. a group of four synapsed chromatids that… …   New Collegiate Dictionary

  • tetrad — /te trad/, n. 1. a group of four. 2. the number four. 3. Cell Biol. a group of four chromatids formed by synapsis at the beginning of meiosis. 4. Chem. a tetravalent or quadrivalent element, atom, or group. [1645 55; < Gk tetrad (s. of tetrás)… …   Universalium

  • tetrad — [ tɛtrad] noun technical a group or set of four. Origin C17: from Gk tetras, tetrad four, a group of four …   English new terms dictionary