Chromatids

Part of speech: noun

Definitions

1. Duplicated strands of DNA that are joined together and are critical for proper segregation during cell division
2. Identical copies of a chromosome that help ensure equal distribution of genetic material during mitosis and meiosis
3. Two identical halves of a replicated chromosome joined at a central region, crucial for genetic material distribution during cell reproduction

Etymology: Chromatids are named for colour, which is not what their structure has to do with it. In 1888, the German anatomist Heinrich Wilhelm Waldeyer coined "chromosome" from the Greek "chrōma" (colour) and "sōma" (body), because these threadlike bodies in the nucleus took up stains so readily in microscope slides. Chromatids came later as a further technical coinage from the same root, referring to each of the two identical copies that a chromosome forms when its DNA is duplicated before cell division. The suffix "-id" is the standard Greek-derived ending used in biology and chemistry for a part or a particle, so the word is essentially "little colour-body" in its construction. Its meaning rests entirely on modern cell biology, and the ancient Greeks had no notion of chromosomes or of DNA.