Final answer:
The cell cycle at key checkpoints is controlled by regulatory proteins, specifically Cyclin and Cyclin-dependent kinases. They act as traffic signals, directing the cell's progression through different phases. Their dysfunction can lead to uncontrollable cell division, such as in cancer.
Step-by-step explanation:
The control of the cell cycle at key checkpoints is mainly held by regulatory proteins. These checkpoints work like traffic lights, signaling the cell when to move from one phase to another. There are primarily two families of regulatory molecules that control the progression of a cell through the cell cycle; these include Cyclin and Cyclin-dependent kinases (Cdks).
Cyclins are proteins that are produced by cells during specific phases of the cell cycle, particularly the G1 (Gap 1), S (synthesis), and G2 (Gap 2) phases. They activate Cdks, initiating the progression to the next stage of the cycle.
Cyclin-dependent kinases (Cdks) are another group of proteins that cooperate with cyclins to pass the cell through different checkpoints. Without the right level of cyclin presence, Cdks remain inactive, preventing the cell from proceeding to the next phase.
The cell cycle, therefore, is carefully controlled by these proteins to ensure accurate duplication and division of cells. If these checkpoints fail or misdeed signals, it can lead to uncontrolled cell division, as seen in conditions like cancer.
Learn more about Cell Cycle Regulation