noun, singular: chromatid
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 chromosomes during the late stages of cell division
During the synthesis phase, the DNA molecule in the chromatin is replicated. As a result, the chromatin would have two DNA molecules 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 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, less distinct 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 chromatin) joined by a kinetochore during mitosis.
Word origin: Greek khrōma, khrōmat- ("color")