A chromosome is a packaged and organized structure containing most of the DNA of a living organism. Most prokaryotic cells have a set of chromosomes (46 in humans) with the genetic material spread among them.
During most of the duration of the cell cycle, a chromosome consists of one long double-helix DNA molecule (with associated proteins). During S phase, the chromosome gets replicated, resulting in an X-shaped structure called a meta phase chromosome. Both the original and the newly copied DNA are now called chromatic. The two "sister" chromatic are joined together at a protein junction called a cerement (forming the X-shaped structure).
