3.24c Mitosis (3)

Notes


Process of Mitosis


-------------- START OF MITOSIS ---------------

1. Interphase (resting state) = nucleus visible, but chromosomes are not

2. Prophase = Break down of nuclear membrane (nucleus breaks down)-> chromosome visible as a 'pair of chromatids'

3. Pro-metaphase = Inside cell (no nucleus remains), network of protein molecules (spindle/fibres) extends from one pole of the cell to the other:
-> Pair of chromatids join onto protein fibre in centre (via centromere)

4. Metaphase = Pair of chromatids joined onto protein fibre in 'spindle' via centromere.
-> Chromosomes are arranged in the 'equator' of cell

5. Anaphase = 'spindle' fibre shortens -> splits pair of chromatids in opposite directions

6. Telophase = Two nuclei form at opposite ends of the cell, around the seperated chromatids.

--------------------- END OF MITOSIS -----------------------

(7.) Cyto-Kinesis (not regarded as part of mitosis) = Cell begins to move inward dividing cytoplasm in half -> Membrane fuses across equator = Two cells each containing a chromosome (same as parental cell)

-> Human: 23 pairs undergo mitosis at the same time

(http://www.ba-education.com/dna/mitosis.jpg)