Cytokinesis

Cytokinesis is the term given to the division of a cell into two daughter cells. Cytokinesis in all cells requires the resolution of the single lipid bilayer of the parent cell into separate bilayers enclosing the two daughter cells, yet cytokinesis mechanisms differ markedly in different cell types. In bacteria, a ring of FtsZ protein filaments constricts the membrane. FtsZ-like proteins operate in some Archeal species, but others use a different mechanism. In plants, vesicles are deposited by microtubules in the centre of the cell to create sheets of membrane that grow outwards until they reach and fuse with the cytoplasmic membrane. In animal cells, actin and myosin form a contractile ring, which draws the membrane inwards. Bundled microtubules and vesicle trafficking then complete the separation (abscission). In all cases, cytokinesis closely follows chromosome segregation and constriction occurs between the separating chromosomes to ensure the genetic integrity of the daughter cells.