The Cell Cycle

First part of the division

Chromosomes aren't visible

Cell looks like a condensed ball

Gets ready for the four stages

By the end, the cell contains enough cell contents to produce two new cells

 Chromosomes become shorter and thicker, therefore making them visible.

The Chromosomes/Chromatids are held together by Centromeres 

 Spindle forms from the microtubules  (3D Structure)

Centrioles move to opposite sides of cell

Therefore forming the 'two poles' of the Spindle

Next phase Metaphase is signalled when Nucear Envelope Breaks down

Nuclear Envelope Breaks down

Chromosomes move to equator

Centromeres attach to spindle

So chromosomes are lined up 

Centromeres split

Spindle fibres shorten, pulling the chromatids towards the poles

Two halves of each centromere pulled in opposite direction

Spindle Breaks down

(Reverse of Prohase)

Chromosomes unravel 

Nuclear Envelope reforms

So the two sets of genetic information become enclosed in seperate nuclei

It is the final re-organisation into two new cells

Cell surface membrane constrics around the centre of the cell

Ring of protein filaments contract until the protein is divided into two new cells

Actin and Myosin (muscle contraction proteins) may be responsible for this division