Flashcards in Mitosis Deck (8)
Importance of mitosis
- Mitosis ensures that both daughter cells produced when a parent cell divides are genetically identical.
- Needed for growth of multicellular organisms and for repairing damaged tissues.
- Some animals, plants and fungi also use it to reproduce asexually.
- PMAT+C (Prophase, Metaphase, Anaphase, Telophase + Cytokinesis)
- Before replication, 1 chromosome has 1 chromatid (strand).
- After replication, chromosome has 2 chromatids.
- Centromere is the middle region where 2 chromatids are joined together.
- 2 strands on the same chromosome are called sister chromatids.
1. Chromosomes condense, getting shorter and fatter.
2. Centrioles start moving to opposite ends of the cell, forming a network of protein fibres across it called the spindle.
3. Nuclear envelope breaks down and chromosomes lie free in cytoplasm.
1. Chromosomes line up on the spindle equator and become attached to spindle by their centromere.
1. Centromeres divide, separating each pair of sister chromatids.
2. Spindles contract, pulling chromatids to opposite ends of the cell, centromere first.
1. Chromatids reach opposite poles on spindle.
2. They uncoil and become long and thin again.
3. They're now called chromosomes again.
4. A nuclear envelope reforms around the 2 groups of chromosomes.
5. So there are 2 nuclei.
1. The cytoplasm divides.
2. In animal cells a cleavage furrow forms around the middle of the cell.
3. There are now 2 daughter cells that are genetically identical to the original cell and to each other.