noun, plural: chromatids
Either one of the two strands joined together by a single centromere, formed from the duplication of the chromosome during the early stages of cell division and then separate to become individual chromosome during the late stages of cell division
During the synthesis phase, the DNA in the chromatin is replicated. As a result, the chromatin would have two DNAs in preparation for cell division, e.g. mitosis. During prophase of mitosis, the nuclear envelope and the other organelles disintegrate while the chromatins condense and become more distinct. At this point, the chromatins are referred to as chromosomes. Each chromosome is comprised of two strands joined by a kinetochore and either one of the two strands is called a chromatid. During the last phases of mitosis, the chromatids separate and move toward opposite poles of the cell. The division of the cell into two results in each daughter cell with a set of chromatids that eventually revert into the thin, indistinct chromatin, each containing a single strand of DNA.
The term chromatid was proposed by Clarence Erwin McClung (1900) for each of the four threads making up a chromosome-pair during meiosis.Later, the term was also used to refer to either one of the two structures (of a chromosome) joined by a kinetochore during mitosis.
Chromatids may be classified as sister chromatids or non-sister chromatids.
Word origin: Greek khrōma, khrōmat– (“color”)