With the exception of gametes, all new somatic cells in all multicellular organisms are formed through the process of mitosis. What must occur with the DNA in the original cells in order for mitosis to make new cells?
In order for mitosis to make new cells, the DNA in the original cell must replicate itself. Before mitosis, the DNA in the original cell undergoes a process called replication, where each chromosome is duplicated to create two identical copies called sister chromatids. This replication process occurs during the interphase of the cell cycle, specifically during the S (synthesis) phase. Once the DNA has been replicated, the duplicated chromosomes condense and become visible under a microscope. The cell then enters mitosis, during which the duplicated chromosomes are separated and distributed evenly into two new daughter cells. Therefore, the original DNA must replicate before mitosis can occur and new cells can be formed.
