Animal Cells:
* Cleavage Furrow Formation: Cytokinesis begins with the formation of a cleavage furrow, an indentation on the cell surface.
* Actin and Myosin: This furrow is formed by a ring of microfilaments composed of actin and myosin proteins, which contract, pulling the cell membrane inward.
* Cell Membrane Invagination: As the furrow deepens, the cell membrane eventually pinches off, separating the two daughter cells.
Plant Cells:
* Cell Plate Formation: Plant cells lack the flexibility for furrow formation. Instead, cytokinesis involves the construction of a new cell wall, called the cell plate, between the daughter cells.
* Golgi Apparatus Involvement: The cell plate originates from the Golgi apparatus, which produces membrane-bound vesicles containing cell wall material (cellulose, hemicellulose, and pectin).
* Vesicle Fusion: These vesicles migrate to the middle of the dividing cell and fuse together, forming a flattened sac called the cell plate.
* New Cell Wall Formation: The cell plate gradually expands outwards, eventually fusing with the existing cell walls, thus dividing the cell into two daughter cells with their own cell walls.
Key Differences:
* Mechanism: Animal cells use a contractile ring to pinch the cell membrane inwards, while plant cells build a new cell wall from vesicles.
* Location: The cleavage furrow forms at the cell surface in animal cells, whereas the cell plate forms in the middle of the dividing cell in plant cells.
* Structures involved: Animal cytokinesis relies on actin and myosin filaments, while plant cytokinesis utilizes the Golgi apparatus and cell wall material.
In essence, the rigid cell wall of plants necessitates a different strategy for cytokinesis, resulting in the formation of a cell plate rather than a cleavage furrow.
