1.6 - A - Cell Cycle & Interphase
The cell cycle is a sequence of events between one cell division and the next. It has two main phases:
Each of the phases of the cell cycle involves many important tasks. Cyclins are a group of proteins that make sure tasks are performed at the correct time. They also make sure that the cell cycle only moves forward when it is appropriate. If errors have been made or if growth is inadequate, they cyclins will not allow the cell cycle to proceed.
Cyclins function by binding to cyclin-dependent kinases, which become active. They trigger other proteins to become active that carry out tasks specific to one of the cell cycle phases.
As shown in the graph to the left, there are four main types of cyclin. The cell cycle does not progress until the appropriate cyclin has reached its treshold concentration.
Controlling the cell cycle at each phases prevents errors from being made during cell growth and cell division. It also ensures that cells only divide when new cells are needed, at not at other times.