Final answer:
The long period between one mitosis and the next in the cell cycle is called interphase, which includes the G₁, S, and G₂ phases where the cell grows, replicates DNA, and prepares for cell division.
Step-by-step explanation:
The long period in the cell cycle between one mitosis and the next is known as interphase. Interphase is the time during which the cell engages in normal growth and prepares for cell division. This preparatory phase includes three subphases: the G₁ phase (First Gap), S phase (Synthesis of DNA), and G₂ phase (Second Gap). During the G₁ phase, the cell increases in size and prepares the building blocks for DNA replication. In the S phase, the actual replication of DNA occurs. The G₂ phase involves further growth and preparation for the division of the duplicated DNA. After interphase, the cell enters the mitotic phase, which includes mitosis—also known as karyokinesis—and cytokinesis, ultimately leading to the formation of two daughter cells.
The interphase is critical as it is during this period that the cell must meet several internal and external conditions to proceed with successful cell division. The process of mitosis ensures that each daughter cell receives an exact copy of the cell's genetic material, and cytokinesis divides the cytoplasm, creating two separate cells. These processes are tightly regulated through a series of checkpoints that ensure cells only proceed to the next stage if certain conditions are met. Any disruptions in these processes can lead to diseases such as cancer.