Cell Division

Cell Division

 There is two types of cell division in plants and animals

Mitosis

Occurs in all cells except gametes. In the daughter cells the chromosomes are in pairs, in humans 23 pairs of chromosomes (diploid)

• Interphase – the cell is carrying out it’s normal function. It increases in size, copies of organelles are made, reproduces DNA, the chromosomes replicate and there is an increase in metabolic activity to produce ATP.

• Prophase – chromosomes condense (now a pair ofchromatids). Centrioles replicate and move to opposite poles and lay the spindle fibres(microfibrils). Nuclear membrane breaks down leaving the chromatids free in the cytoplasm.

• Metaphase – chromatids line up at the equator of the cell, and become attached to certain spindle fibres at thecentromere, these contract slightly

• Anaphase – quick phase, spindle fibres contract pulling the chromatids apart at the centromere. The separated chromatids are pulled to the poles centromere first.
• Telophase – chromosomes uncoil and lengthen, spindle breaks down and 2 nuclear membranes are formed

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