Biology 30 – Mitosis And Meiosis Practice Test

In plant cells, the key event of cytokinesis is the formation of a cell plate at the center of the cell. Vesicles derived from the Golgi apparatus accumulate at the center and fuse with one another to create this cell plate. As the plate enlarges, it extends toward the edges of the cell and eventually fuses with the existing plasma membranes, becoming the separating cell walls and new membranes between the two daughter cells. This central plate formation fits plants because their rigid cell walls prevent the membrane from simply pinching inward like a contractile ring would do in animal cells. In contrast, animal cells use a contractile actin ring that constricts the cell membrane to form a cleavage furrow, splitting the cell from the outside in. The idea that cytokinesis simply follows the nucleus divisions (with the nucleus dividing first) is about the timing of mitosis and cytokinesis, but the distinctive mechanism in plants is the formation of the central cell plate rather than a peripheral pinching.