Cell Cycle

The cell cycle is defined as the series of events that leads to the formation of a new cell from an existing one; the phenomenal changes that build up a new cell population all occur within this cycle, which was first described by Prevost and Dumans in 1824. The cycle is conventionally split into two broad parts: interphase, during which the cell grows and prepares its DNA and organelles for division, and the M phase, comprising mitosis (nuclear division) and cytokinesis (cytoplasmic division). Figure 7.1 shows the cycle as a continuous loop rather than a straight line, which captures the fact that a daughter cell can itself go on to divide again. In a typical actively proliferating eukaryotic cell the whole cycle takes about 24 hours, but the two parts are very unequal in length: interphase alone consumes roughly 95% of the cycle time, while mitosis and cytokinesis together occupy only about an hour. This lopsided division of time makes sense biologically - interphase is when the cell does the bulk of its metabolic work, synthesises n …