A chromosome is a DNA molecule (deoxyribonucleic acid) that contains part or all the genome (genome) of an organ. Most eukaryotic chromosomes encode proteins that bind, assisted by chaperone proteins, that bind and stabilize a DNA molecule to prevent it from becoming an uncontrolled tangle. This three-dimensional genome structure plays a major role in transcriptional regulation.

Chromosomes are usually visible under a bright light only when the cell is below the cell image. Before this happens, the entire chromosome is copied once (phase S), and the copy is then joined to the original by a centromere, resulting in an X-shaped structure when the centromere is located in the center of the chromosome or in both arms. formation when the centromere is located near the other end. The original chromosome and copy are now called sister chromatids. During measurement, the X-form structure is called the metromase chromosome. In this form of reduced chromosomes, it is easy to isolate and read. In animal cells, chromosomes reach their highest anaphase level during chromosome segregation.