Chapter 6 Section 2 Cell Cycle
The Life of a Eukaryotic Cell The Cell Cycle The cell cycle is a repeating sequence of cellular growth and division during the life of an organism. A cell spends 90 percent of its time in the first three phases of the cycle, which are collectively known as the interphase.
The Cell Cycle The five phases of the cell cycle are: First growth (G1) phase: Cell grows rapidly Cell carries out routine functions
The five phases of the cell cycle are: Synthesis (S) phase: DNA is copied
The five phases of the cell cycle are: Second growth (G2) phase: Cell continues to grow Cell prepares to divide its nucleus
The five phases of the cell cycle are: Mitosis Process that the nucleus divides into two nuclei.
The five phases of the cell cycle are: Cytokinesis Process that equally divides the cytoplasm Pinches the parent cell into two new daughter cells
Control of the Cell Cycle The cell has key checkpoints (inspection points) at which feedback signals from the cell can trigger the next phase of the cell cycle.
Control of the Cell Cycle Other feedback signals can delay the next phase to allow for completion of the current phase (yellow or red light).
Control of the Cell Cycle Control occurs at three principal checkpoints: Cell growth (G1) checkpoint: Is the cell too big? If yes, the cell will prepare to divide If no, the cell will continue to grow.
Control occurs at three principal checkpoints: DNA synthesis (G2) checkpoint: Is the DNA properly replicated: If yes, mitosis will occur. If no, DNA will repaired.
Control occurs at three principal checkpoints: Mitosis checkpoint: Did the nucleus properly divide? If yes, cytokinesis will occur. If no, mitosis must be completed.
When Control is Lost: Cancer Certain genes contain the information necessary to make the proteins that regulate cell growth and division.
When Control is Lost: Cancer If one of these genes is mutated, the protein may not function, and regulation of cell growth and division can be disrupted. Cancer: the uncontrolled growth of cells.