- a group of four.
- the number four.
- Cell Biology. a group of four chromatids formed by synapsis at the beginning of meiosis.
- Chemistry. a tetravalent or quadrivalent element, atom, or group.
- a group or series of four
- the number four
- botany a group of four cells formed by meiosis from one diploid cell
- genetics a four-stranded structure, formed during the pachytene stage of meiosis, consisting of paired homologous chromosomes that have each divided into two chromatids
- chem an element, atom, group, or ion with a valency of four
- ecology a square of 2 × 2 km used in distribution mapping
n.1650s, from Greek tetras (comb. form tetrad-) “group of four” (see tetra-). n.
- A group or set of four.
- A tetravalent atom, radical, or element.
- A group of four chromatids formed from each of a pair of homologous chromosomes that split longitudinally during the prophase of meiosis.
- A four-part structure that forms during prophase I of meiosis and consists of two homologous chromosomes, each composed of two identical chromatids. During prophase I of meiosis, one chromosome exchanges corresponding segments of genetic material with the other chromosome in the tetrad in the process called crossing over. See more at meiosis.
- A group of four cells, as of spores or pollen grains, formed from a parent cell by meiosis. As part of the process of spermatogenesis, a spermatocyte divides into a tetrad of four spermatids, cells which go on to develop into sperm. See more at spermatogenesis.