Final answer:
DNA replication takes place during the S phase of the cell cycle, resulting in two identical sister chromatids for each chromosome. The centrosome is also duplicated, setting the stage for mitosis and ensuring that each daughter cell gets a full set of chromosomes.
Step-by-step explanation:
DNA replication occurs during the S phase (synthesis phase) of the cell cycle. During interphase, more specifically in the S phase, nuclear DNA is in a semi-condensed chromatin configuration, and this is where the replication of DNA takes place. This process leads to each chromosome being composed of two identical copies known as sister chromatids, which are essential for the following mitosis or cell division stages.
During the S phase, not only is the DNA replicated but also the Centrosome, which consists of a pair of centrioles. These structures are crucial for the formation of the mitotic spindle, the apparatus responsible for the correct segregation and movement of chromosomes during mitosis. This is to ensure that each daughter cell receives a complete set of chromosomes, which is fundamental for proper cell function and division.