Final answer:
In plant cell cytokinesis, a cell plate forms and extends to the plasma membrane, starting at the spindle apparatus. The plate is built by Golgi vesicles and becomes a new cell wall that separates the daughter cells.
Step-by-step explanation:
Cytokinesis in plant cells is a crucial process that involves the division of the cytoplasm and organelles between two daughter cells following nuclear division (mitosis or meiosis). Unlike animal cells, plant cells have a unique mechanism for cytokinesis, which includes the formation of a cell plate.
The process of plant cell cytokinesis begins during telophase, the final stage of mitosis. At this point, the spindle apparatus, responsible for segregating chromosomes, disassembles, and a structure called the phragmoplast becomes apparent. The phragmoplast consists of microtubules and associated vesicles derived from the Golgi apparatus.
Golgi vesicles containing cell wall materials, such as pectins and other polysaccharides, accumulate at the center of the cell and align along the phragmoplast. These vesicles fuse to form a flattened, disk-like structure known as the cell plate. The cell plate starts to extend outward from the center towards the cell's periphery, ultimately reaching and merging with the plasma membrane.
As the cell plate enlarges, it fuses with the existing plasma membrane, dividing the cytoplasm into two distinct compartments. This fusion occurs at a right angle to the spindle apparatus, ensuring the proper alignment and separation of the daughter cells. The site of fusion corresponds to the former location of the metaphase plate during earlier stages of mitosis.
Over time, the cell plate undergoes structural modifications and transforms into a mature cell wall, establishing a physical barrier between the two daughter cells. This new cell wall reinforces the structural integrity of each cell and ensures their independent functionality.
In summary, plant cell cytokinesis involves the formation of a cell plate, initiated by Golgi vesicles and guided by the phragmoplast. This temporary structure matures into a new cell wall, completing the process of cell division and contributing to the development of two genetically identical daughter cells with distinct boundaries.