mitosis

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:

•  prophase
• metaphase
•  anaphase
• telephase

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.)

Metaphase=Meet

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.

Anaphase=Away

end stage:

• 2 sets of daughter chromatids reach opposite poles
• nuclei and muclear membrane reforms

2 identical nuclei are the product.