tetrad

1. a group or series of four 2. the number four 3. Botany a group of four cells formed by meiosis from one diploid cell 4. Genetics a four-stranded structure, formed during the pachytene stage of meiosis, consisting of paired homologous chromosomes that have each divided into two chromatids 5. Chem an element, atom, group, or ion with a valency of four 6. Ecology a square of 2 × 2 km used in distribution mapping

Tetrad

(1) A group of four haploid cells formed by meiosis from a single diploid cell. Tetrads are typical of plants. In mosses, fungi, and algae, such four-celled groups may remain for a long time within the membrane of the parent cell. By isolating the cells of the tetrad in these organisms, vegetative offspring may be obtained and the genetic division in each meiosis may be studied by means of tetrad analysis. Ordered arrangements of cells may occur in tetrads; the chromosome groups in the cells of such tetrads reflect the order in which the chromosomes of two successive meioses separate. These cells, called linear asci, are typical of some ascomycete fungi.

(2) In tetrad analysis, the four cultures obtained by the vegetative propagation of spores formed after the meiosis of a single diploid cell.

(3) A structure composed of four connected chromatids. It is observed in animal cells during the prophase of the first, or reductive, division of meiosis. Such tetrads are also called bivalents.

I. I. TOLSTORUKOV

tetrad

[′te‚trad] (cell and molecular biology) A group of four chromatids lying parallel to each other as a result of the longitudinal division of each of a pair of homologous chromosomes during the pachytene and later stages of the prophase of meiosis.

tetrad

[tet´rad] 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 chromosomal elements formed in the pachytene stage of the first meiotic prophase; (3) a square of cells produced by division into two planes of certain cocci (Sarcina).

tet·rad

(tet'rad), 1. A collection of four things having something in common, such as a deformity with four features, for example, Fallot tetralogy. Synonym(s): tetralogy2. In chemistry, a quadrivalent element. 3. In heredity, a bivalent chromosome that divides into four chromatids during meiosis. [G. tetras (tetrad-), the number four]

tetrad

(tĕt′răd′)n.1. A group or set of four.2. A tetravalent atom, radical, or element.3. Biology a. A four-part structure that forms during the prophase of meiosis and consists of two homologous chromosomes, each composed of two sister chromatids.b. A group of four haploid cells, such as spores, formed by meiotic division of one mother cell.

te·trad′ic adj.

tet·rad

(tet'rad) 1. A group of four things having something in common, such as a deformity with four features, e.g., Fallot tetralogy.
Synonym(s): tetralogy. 2. chemistry A quadrivalent element. 3. genetics A bivalent chromosome that divides into four during meiosis. [G. tetras (tetrad-), the number four]

tetrad

the four homologous CHROMATIDS which associate during prophase (the PACHYTEN stage) and metaphase of MEIOSIS and are involved in CROSSING OVER.
the four haploid cells produced by one complete meiotic division.

tet·rad

(tet'rad) Collection of four things having something in common, such as a deformity with four features, e.g., tetralogy of Fallot. [G. tetras (tetrad-), the number four]

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Synonyms for tetrad

noun the cardinal number that is the sum of three and one

Synonyms

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