Prophase is a stage of mitosis in which the chromatin conenses into a highly ordered structure called a chromosome (it is at this stage giemsa staining can be applied to elicit G-banding in chromosomes). This process, called chromatin condensation, is mediated by the condensin complex. Since the genetic material has been duplicated, there are two identical copies of each chromosome in the cell. Identical chromosomes, called sister chromatids, are attached to each other at a DNA element present on every chromosome called the centromere.