Mitosis

Mitosis is the process of asexual (single organism) division. This is how cells split apart (into four cells).

The process can be split into P-M-A-T, or:

Prophase

Metaphase

Anaphase

Telophase

The starting point is Prophase:

Chromatin condenses and becomes `super-coiled` chromosome/s. The chromosomes come together as homologous pairs to form a Bivalent. Each pair has a maternal and a paternal chromosome, and both chromosomes are identical.

None sister chromatids wrap together at a Chiasma. Sections are swapped (hence some mutations occur).

The nuclear enveloped and nuclear membrane now break down, and spindle fibres form from Centrioles at each end of the cell.

Metaphase:

The Bivalents (homologous pairs) all line up at the equator (the centre of the cell), and attach to the grown spindle fibres. They are then arranged randomly so each member of a pair face the opposite ends of the cell. The chiasma is still in place.

Anaphase:

The Bivalents are pulled apart (with one chromosome per side) by the spindle fibres towards the centrioles. Any non-sister chromatids entwined at this point are pulled apart (so some chromosomes have different codings as parts of one are attached to another and vice versa).

Telophase:

New nuclear envelopes form around the chromosomes. The chromosomes themselves now uncoil back into chromatin. The two cells are split in the centre by Cytokinesis.

This whole process occurs twice to produce 4 new cells, the second time by the original cell and the new copy.

 This process happens twice - the daughter cells are used in the `second round`.

This shows when Mitosis takes place - during the `M` stage. G1 and G2 are Growth Stages, and S is  the synthesis of new DNA. Go is when a cell stops the cell division cycle.