Cytokinesis: The Division of the Cytoplasm
1. Animal cells divide by a furrowing (a “pinching in” or constriction) of the plasma
membrane.
2. Microfilaments of actin and the motor protein filament myosin first form a ring
beneath the plasma membrane.
3. Actin and myosin contract to produce the constriction.
4. Plants have cell walls and the cytoplasm divides differently.
• After the spindle breaks down, vesicles from the Golgi apparatus appear in the
equatorial region.
• The vesicles fuse to form a new plasma membrane, and the contents of the
vesicles combine to form the cell plate, which is the beginning of the new cell
wall.
5. Organelles and other cytoplasmic resources do not need to be distributed equally in daughter cells, as long as some of each are present in both new cells to assure additional generation of organelles as needed.
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