Figure %: The Cell Cycle

The cell cycle is the recurring sequence of events that includes the duplication of a cell's contents and its subsequent division. This SparkNote will focus on following the major events of the cell cycle as well as the processes that regulate its action. In this and the following SparkNotes on cell reproduction, we will see how the cell cycle is an essential process for all living organisms. In single-cell organisms, each round of the cell cycle leads to the production of an entirely new organism. Other organisms require multiple rounds of cell division to create a new individual. In humans and other higher-order animals, cell death and growth are constant processes and the cell cycle is necessary for maintaining appropriate cellular conditions.

As we discussed in the Introduction to Cell Reproduction, the goal of cellular reproduction is to create new cells. The cell cycle is the means by which this goal is accomplished. While its duration and certain specific components vary from species to species, the cell cycle has a number of universal trends.

  1. DNA packaged into chromosomes must be replicated.
  2. The copied contents of the cell must migrate to opposite ends of the cell.
  3. The cell must physically split into two separate cells.

We will discuss the general organization of the cell cycle by reviewing its two major phases: M Phase (for mitosis) and interphase. Interphase is generally split into three distinct phases including one for DNA replication. We will finish with a discussion of the elements that control a cell's passage through these various stages. The cell cycle is very highly regulated to prevent constant cell division and only allows cell that have met certain requirements to engage in cell division.