- Mitosis is the nuclear division of a cell to produce two identical cells, thus multiplying the population exponentially.
- There are five phases of mitosis, which are preceded by interphase and followed by cytokinesis.
The follow are the combined seven steps of mitosis:
1. Interphase: not usually considered a step in mitosis, the cell spends most of its life in interphase. There are three stages to interphase.
| - G1: The longest stage of interphase, the cell continues on its merry way as a cell, carrying out protein synthesis and other cell jobs. The chromosomes are unable to be discerned, and the nucleus is the only thing visible (with staining).
- S: The cell is preparing for mitosis by replicating the DNA. All chromosomes now have chromatin, or two sets of DNA per chromosome.
- G2: The cell continues to do it's cell duties, but near the end of G2, the cytoplasm organelles will replicate in order to be prepared for cell division during mitosis.
|
2. Mitosis
| - Prophase: Chromatin (what chromosomes are made of) condense. Each chromosome appears as a linked chromatid. Spindles are formed.
- Prometaphase: The nuclear membrane dissolves and the fibers of the spindle connect to the chromatids. The chromatids are linked by kinetochores.
- Metaphase: The chromatids align in the middle of the cell, forming the metaphase plate.
- Anaphase: The chromatids separate and the spindles pull each separate piece to their side of the cell, ensuring that each new cell will have a copy of the chromosome from the parent cell.
- Telophase: The chromosomes are in the opposite sides of the cell, and membranes form around them. Spindle fibers may dissolve.
|
3. Cytokinesis: not usually considered a step in mitosis, animal cells and plant cells undergo different processes during cytokinesis.
| - In animal cells: a fibrous protein ring called actin forms around the center of the cell and contracts, pinching the cell into two.
- In plant cells: a cell plate is synthesized between the two cells, in order to create a cell wall.
|
And thus, mitosis is complete!
Animal cell mitosis
Click image to be taken to the source.
Plant cell mitosis
Click image to be taken to the source.
