KEY CONCEPT Cells have distinct phases of growth, reproduction, and normal functions.
The cell cycle has four main stages. Cell cycle-is the regular pattern of growth, DNA duplication, and cell division that occurs in eukaryotic cells.
The 4 main stages of the cell cycle: 1) Gap 1 (G1)- Cell carries out normal functions, increases in size, and organelles increase in number. Cells spend most of their life in this stage. 2) Synthesis (S)- Cells make a copy of nuclear DNA. 3) Gap 2 (G2)- Cells continue normal function and continue to grow. Cells must go through certain checkpoints, like size, number of organelles, DNA copied, etc. 4) Mitosis (M)- Cell division stage. Consists of 2 stages: A) Mitosis- Division of cell nucleus and its contents. B) Cytokinesis- Process that divides cell cytoplasm, resulting in two identical daughter cells.
Cells divide at different rates. The rate of cell division varies with the bodies need for those types of cells. In human cells, S, G2, and M takes about 12 hours Length of the G1 stage depends on cell type Rate of division is greater in the embryo and kids G0 stage- stage where some cells rarely, if ever, divide. Example Lymphocytes (White Blood Cells).
Cell size is limited. Volume increases faster than surface area.
Surface area must allow for adequate exchange of materials. Cell growth is coordinated with division. Cells that must be large have unique shapes.