- Created by: Katie Smith
- Created on: 10-04-11 19:43
For a cell to divide, it either goes through mitosis or meiosis.
The most common form of cell division is mitosis. Meiosis is purely limited to gametes.
Mitosis has four stages; Prophase, Metaphase, Anaphase and Telophase. There is also Interphase which takes up the majority of the cell cycle.
During interphase, the cell carries out its day to day functions.
Also, DNA and organelle replication occurs.
The cell has more ATP at this stage as it needs more energy ready for division.
The chromosomes in the nucleus get short and fat (condense) in this stage.
Only once this happens, are we able to see them through a microscope.
Centrioles, small fibrous bundles, move to each end of the cell and the nuclear envelope breaks down and allows the chromosomes to move freely in the cytoplasm.
The free chromosomes line up along the equator of the cell.
Their centromeres (the thing that joins them together in the middle) attach to a spindle fibre which is in turn attached to either centriole.
The centromeres duplicate at this point, creating two sister chromosomes.
The spindle fibres contract and pull the chromosomes to either end of the cell with the centromeres leading.
Once the chromosomes are separated, the spindle fibres detach themselves.
The chromosomes then uncoil and become long and thin again (we can no longer see them under a microscope).
Nuclear envelopes form around the groups of chromosomes at each end, creating two nuclei.
The cytoplasm then divides, creating two new daughter cells.
The cell then goes back to interphase and starts the cycle all over again.