How does cytokinesis differ between plant and animal cells, and what occurs during this process after mitosis?
How does cytokinesis differ between plant and animal cells, and what occurs during this process after mitosis?
Answer
Cytokinesis is the process that divides the cytoplasm of a parent cell into two daughter cells, following mitosis. While the fundamental goal of cytokinesis is the same in both plant and animal cells—creating two distinct daughter cells—the mechanisms and structures involved differ significantly due to the presence of a rigid cell wall in plant cells. Here’s a detailed comparison of cytokinesis in plant and animal cells:
Differences in Cytokinesis Between Plant and Animal Cells
1. Mechanism of Division
- Plant Cells:
- Cytokinesis occurs through the formation of a cell plate. Vesicles derived from the Golgi apparatus transport cell wall materials to the center of the dividing cell, where they fuse to form a new cell wall that separates the daughter cells. This process is known as centrifugal division because the cell plate grows outward from the center toward the edges of the cell.
- Animal Cells:
- In contrast, animal cells undergo cytokinesis by forming a cleavage furrow. This furrow is created by a contractile ring composed of actin and myosin filaments, which constricts the cell membrane from the outside toward the center, effectively pinching the cell into two. This is referred to as centripetal division.
2. Structural Components
- Plant Cytokinesis:
- The formation of the cell plate involves vesicles that carry pectins and other materials necessary for building new cell walls. The growing cell plate eventually fuses with the existing plasma membrane, leading to the formation of two separate daughter cells, each encased in its own cell wall.
- Animal Cytokinesis:
- The cleavage furrow deepens as myosin II filaments contract, pulling the plasma membrane inward until it pinches off, resulting in two separate daughter cells without a rigid wall.
3. Directionality of Division
- Plant Cells: The division is centrifugal; it starts from the center and moves outward.
- Animal Cells: The division is centripetal; it starts at the periphery and moves inward.
4. Timing and Coordination
Both processes begin during or after anaphase (the stage of mitosis where sister chromatids are separated). However, they are tightly regulated to ensure that cytokinesis occurs only after chromosomal separation is complete, maintaining genomic integrity in both daughter cells.
Summary of Events After Mitosis
After mitosis concludes with telophase:
- In both plant and animal cells, cytokinesis begins to partition the cytoplasmic contents.
- In plant cells, vesicles fuse at the metaphase plate to form a new cell wall (cell plate), while in animal cells, actin and myosin form a contractile ring that leads to cleavage furrow formation.
- Once cytokinesis is complete, each daughter cell enters interphase, where it will grow and prepare for its next division cycle.
Sourav
