Cytokines

Abstract

<jats:title>Abstract</jats:title> <jats:sec> <jats:label /> <jats:p>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.</jats:p> </jats:sec> <jats:sec> <jats:title>Key Concepts:</jats:title> <jats:p> <jats:list list-type="bullet"> <jats:list-item> <jats:p>To make two cells from one, the DNA needs to be copied, the two copies separated and the cell divided (cytokinesis) so that one DNA copy resides in each daughter cell.</jats:p> </jats:list-item> <jats:list-item> <jats:p>The cytoplasmic membrane of the parent cell must resolve into the two cytoplasmic membranes of the daughter cells.</jats:p> </jats:list-item> <jats:list-item> <jats:p>Cell division frequently involves the formation of a ring of protein filaments that attaches to the membrane and constricts, drawing the membrane inwards.</jats:p> </jats:list-item> <jats:list-item> <jats:p>In many bacterial cells, the main component of this ring is the FtsZ protein. In animal cells, the main components are actin and myosin.</jats:p> </jats:list-item> <jats:list-item> <jats:p>In plant cells, microtubules form across the future site of division and deposit membrane vesicles which fuse to form the new membrane.</jats:p> </jats:list-item> <jats:list-item> <jats:p>In many eukaryote cells, the mitotic spindle allows the DNA to separate, and then signals the cell to determine the plane of division.</jats:p> </jats:list-item> <jats:list-item> <jats:p>In animals, the final separation of daughter cells involves vesicles fusing with the cell membrane.</jats:p> </jats:list-item> <jats:list-item> <jats:p>Errors in cytokinesis have serious implications for cancer.</jats:p> </jats:list-item> </jats:list> </jats:p> </jats:sec>