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Related to tetrad: Tetrad analysis


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



(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.



(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.
References in periodicals archive ?
Pro-orbicules, after exocytosis and generally during tetrad stage, nest on the tapetal plasmalemma, and it is on this lipidic surface that they receive their sporopollenin coat.
Tetrad Investment Bank is in the process of converting from a merchant bank to a commercial bank, for which it needed a robust, scalable and future-ready core banking and surround solutions suite.
In the teleparallel equivalent of general relativity this tetrad field exists as an independent structure.
The tetrad is exegesis on four levels, showing not the mythic, but the logos-structure of each artefact, and giving its four "parts" as metaphor, or word.
In a Tetrad test, four samples, two from one version of the product and two from the other, are presented to a subject who is then asked to group the samples into two groups of two, based on similarity.
By making a null rotation, that is a map from one null tetrad to another null tetrad, that keeps [[xi].
At each point of a differentiable curve a tetrad of mutually orthogonal unit vectors (called tangent, normal, binormal, and trinormal) was defined and constructed.
Teaching Media Ecology or Why My Students Love the Tetrad.
The confirmation of a diagnosis of Bouveret syndrome using plain abdominal films is dependent on the observation of Rigler's tetrad as delineated in his 1941 article (17) (Table 1).
The classic tetrad of symptoms for narcolepsy includes excessive daytime sleepiness (EDS), cataplexy, sleep paralysis, and hypnagogic hallucinations (8).
Bahder (US Army Aviation and Missile Research, Development, and Engineering Center, Redstone Arsenal, Alabama) explores the problem from a relativistic perspective, emphasizing the local measurement process and the use of the tetrad formalism as the best model for relativistic measurements.
Both the PC and the GES algorithms are embedded in the TETRAD IV software (available online at www.