During which phase of the cell cycle does the duplication of chromosomes occur?

The duplication of chromosomes occurs during interphase, specifically in the S phase (synthesis phase) of this stage. Interphase is the phase of the cell cycle where a cell prepares for division and consists of three stages: G1 (gap 1), S (synthesis), and G2 (gap 2). During the S phase, each chromosome is replicated, resulting in two sister chromatids for each chromosome, which are essential for accurate genetic distribution to daughter cells during mitosis or meiosis.

Other phases, such as mitosis and meiosis, focus on the separation of these already duplicated chromosomes but do not involve their duplication. Telophase is part of the mitotic and meiotic processes that occur after chromosomes have already been replicated and separated, leading to the finalization of cell division. Therefore, interphase is the crucial phase for chromosome duplication in preparation for subsequent cell division.