What does a duplicated chromosome consist of?

A duplicated chromosome is made up of two identical chromatids that are connected at a region called the centromere. This structure forms during the cell cycle when DNA replication occurs, specifically during the S phase, leading to the duplication of each chromosome. Each chromatid is an identical copy of the DNA molecule that was originally present, and the centromere serves as the point of attachment for the chromatids, as well as a critical site for the assembly of the mitotic spindle during cell division.

The presence of two chromatids instead of one is crucial for accurate chromosome segregation during mitosis or meiosis. This ensures that when the cell divides, each daughter cell receives an exact copy of each chromosome. Understanding this structure is fundamental in molecular diagnostics, as it reflects the underlying mechanisms of genetic inheritance, stability, and potential mutations that may arise during cell division.