The cell cycle starts with intephase in which DNA is replicated, cyptoplasm and organelles grow.
The next phase is mitosis. this consist of 4 stages:
Cytokinesis is division of the cyptoplasm and may or maynot occur after the cell cycle. for example it doesnt occu in musclecells.
a key thing about mitosis is that it doesnt bring about genetic variation it merely leads to theproduction of 2 identical daughter cells.
1st stage of mitosis. the following happens:
- chromosomes condense and appear shorter and fatter.this enables the chromosomes to be more easily moved.
- the nucleoli dissappear and the nuclear membrane breaks down
- spindle apperatus appears( controll movement of chromosomes)
- in late prophate the spindle apperatus move to opposite poles.
the 2nd stageof mitosis:
- centromeres of the chromosomes line up on the equator of the cell.
- the centromeres divide
- spindle apperatus is fully formed
- one sister chromatid from each chromosome is attached to opposite microtubule at opposite poles
(microtubule is part of the spindle apparatus. sisterchromatids make up the chromosomes. 2 in each chromosome.)
the 3rd stage of mitosis:
- the centromeres separate
- sister chromatids are pulled toopposite poles of the cell by the shortening of the spindle aperatus.
- sister chromatids now referred to as daughter chromosomes.
- 2 sets of daughter chromatids reach opposite poles
- nuclei and muclear membrane reforms
2 identical nuclei are the product.