What controls cell division Why

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The cell cycle

The cell cycle is the cyclic sequence of cell divisions (mitoses) and growth phases (interphases) in dividing (proliferating) tissues.

In the tissues of multicellular organisms, used and dead cells are replaced by cell division. In organisms that are still growing, cell division is also responsible for growth. The cell cycle controls and coordinates the reproduction of cells. To do this, the DNA must first be identically duplicated (replicated) and the chromosomes condensed from it must be correctly divided between the two daughter cells. Furthermore, most cells have to double their cell mass and organelles beforehand. The timing of these diverse processes is coordinated by the cell cycle.

The period between cell divisions, the so-called mitotic phases (M-phases or mitosis), is called interphase. In this the cell grows to the necessary size and many molecular processes take place, of which the doubling of the DNA is the most prominent. The interphase shows three distinct phases, which are designated as G1 (Short for engl. Gap1 "gap 1"), S (synthesis) and G2 are designated.

Within the cell cycle, different proteins interact, which are interpreted as stop or go / start signals at certain phases of the cell cycle (checkpoints). The two most important checkpoints are the G1-Checkpoint immediately before entering the S phase and the second before entering mitosis.

The American Leland Hartwell and the British Paul Nurse and Tim Hunt won the 2001 Nobel Prize in Physiology or Medicine for their discoveries of the key regulators of the cell cycle.

The G1-Phase

The G0-Phase

S phase


M phase