Chiasmata

Part of speech: noun

Definitions

1. Referring to the points where homologous chromosomes exchange genetic material during meiosis
2. indicating the cross-shaped structures formed by such exchanges
3. describing the critical locations that facilitate genetic diversity in sexual reproduction

Etymology: The Greek letter chi, written as an X, gave this term its shape. Ancient Greek "khiazein" meant "to mark with a chi," and from it came "khiasma," a crosswise arrangement or crossing. The same root produced "chiasmus," the rhetorical figure in which phrases are mirrored in reverse order, as in "fair is foul, and foul is fair." In biology, the Greek noun was adopted in its Latinized form, and the plural "chiasmata" keeps the Greek neuter ending "-mata," which is why the singular is "chiasma." The term describes the points where paired chromosomes cross over each other during meiosis, the cell division that produces sperm and egg cells. Those X-shaped crossings are visible under a microscope, and they mark the places where chromosomes swap segments of genetic material.

Synonyms: crossings, intersections