Cell cycle

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Cell cycle

Cells reproduce (proliferate) through a highly-regulated process of cell division called mitosis where one cell splits into two daughter cells. The cell cycle is a recurring process where the cell replicates all cellular components and verifies the integrity of the genetic code then undergoes mitosis.
The cell cycle begins with the first gap phase (G1). During G1 the cell replicates all of the cellular machinery other than the DNA. The first checkpoint occurs in G1 for the cell to check the DNA to ensure there are no issues before proceeding. The next phase is the synthesis phase (S) where DNA replication occurs. The second gap phase (G2) occurs when the cell stops the progression of the cell cycle for another DNA checkpoint. After being given the signal to proceed, the cell will move into the mitotic phase (M) where the nucleus divides into 2 nuclei and the cell then splits into 2 separate cells. The process will then begin again, unless the cell goes into a dormant state termed G0 or senescence.
Uncontrolled growth (proliferation) is a hallmark of cancer. Therefore the cell cycle must be tightly regulated as this process is often hijacked in cancer. The cell needs to respect the checkpoints in the cell cycle and be able to stop the cell cycle when an aberration in the DNA is detected.
Image courtesy of Wikimedia

Cell cycle