Biology (Combined)
Mitosis and the cell cycle
Overview of Cell Cycle: Introduction to the different phases
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Overview of Cell Cycle: Introduction to the different phases
Overview of the Cell Cycle
The cell cycle is a series of ordered events in a cell leading to its division and duplication of DNA to produce two identical daughter cells.
Interphase
- Interphase is the longest stage of the cell cycle. It is when the cell grows, performs its normal functions, and prepares for division.
- It is divided into G1, S, and G2 phases.
- In the G1 phase, the cell increases in size and synthesises proteins and molecules.
- The S phase (synthesis) is when the cell replicates its DNA.
- The G2 phase is a period of rapid cell growth and protein synthesis during which the cell prepares itself for mitosis.
Prophase
- The first stage of mitosis is prophase. In this phase, the chromatin condenses into distinct chromosomes.
- The nuclear envelope breaks down, and the centrioles begin to move to opposite ends of the cell (poles).
Metaphase
- During metaphase, the chromosomes line up along the metaphase plate (equator) of the cell.
- Spindle fibres from each centriole attach to each sister chromatid at their centromeres.
Anaphase
- In anaphase, the centromeres of each chromosome separate, and identical sets of chromosomes move to opposite ends of the cell.
Telophase and Cytokinesis
- In telophase, a nuclear membrane re-forms around each set of chromosomes, and the chromosomes unwind back into chromatin.
- During cytokinesis, cytoplasm splits and two new cells are formed. Each new cell, now known as daughter cells, enter G1 phase of interphase.
- Cytokinesis is slightly different in plant cells, where a cell wall must also be generated between the new cells. This is done through the formation of a structure called the cell plate.
Remember, understanding the stages of the cell cycle and the process of mitosis is crucial, as they underpin growth and repair in all organisms.
