Question

Contrast telophase in plant and animal mitosis.

Short answer

Answer: The differences in telophase during plant and animal cell mitosis are primarily in the process of cytokinesis. Plant cells undergo cell plate formation, where a cell plate forms between the daughter nuclei and grows outward to create a new cell wall and cell membrane. Animal cells form a cleavage furrow, which is caused by the contraction of actin and myosin filaments and results in the plasma membrane pinching off to create two separate daughter cells.

Step-by-step solution

Understanding Telophase

Telophase is the final stage of mitosis, where the chromosomes decondense, and the nuclear envelope forms around the new daughter nuclei. Cytokinesis, the division of the cell cytoplasm, occurs simultaneously with telophase. Although the general process of telophase is similar in both plant and animal cells, there are differences in how cytokinesis is accomplished and how the dividing cells separate.

Cell Plate Formation in Plant Cells

In plant cells, during telophase, a cell plate forms between the two daughter nuclei. This cell plate is composed of cell wall materials, such as cellulose, and is produced by the Golgi apparatus. The cell plate grows outward from the center of the cell until it reaches and fuses with the plasma membrane, eventually separating the two daughter cells. The new plant cell wall forms along the cell plate, resulting in a new cell wall and cell membrane for each daughter cell.

Cleavage Furrow Formation in Animal Cells

In animal cells, cytokinesis involves the formation of a cleavage furrow during telophase. The cleavage furrow is caused by the contraction of the actin and myosin filaments present in the cell's cytoskeleton. As these filaments contract, they pull the plasma membrane inwards, forming a deepening groove around the equator of the cell. Eventually, the plasma membrane is pinched off at the site of furrow, thus resulting in the formation of two separate daughter cells.

Comparing Cytokinesis in Plant and Animal Cells

The major difference in telophase between plant and animal cells lies in cytokinesis. Plant cells undergo cell plate formation due to the presence of a rigid cell wall, while animal cells undergo cleavage furrow formation due to their more flexible plasma membrane. Additionally, plant cells utilize cell wall materials like cellulose, while animal cells utilize actin and myosin filaments during cytokinesis.

Key concepts

Cell Plate Formation in Plant Cells

Understanding cell division in plant cells requires an exploration of cell plate formation. At the onset of cytokinesis during telophase in plant mitosis, vesicles from the Golgi apparatus move to the center of the cell. As these vesicles coalesce, they form the beginnings of a new structure known as the cell plate.

This cell plate acts as a precursor to the future cell wall that will separate the two daughter cells. Composed of cell wall materials, including cellulose, pectin, and other components, the cell plate extends outward, eventually connecting with the existing cell membrane. Once connected, it creates a partition, effectively dividing the cytoplasm of the plant cell into two halves, each with its own nucleus. Over time, this plate will develop into a fully formed and structurally sound wall, separating the two new cells completely.

Cleavage Furrow in Animal Cells

Unlike plant cells, animal cells accomplish cytokinesis through the formation of a cleavage furrow, a process that reflects the more flexible nature of the animal cell membrane. During telophase, the cell's cytoskeleton plays a vital role as actin and myosin fibers contract, similar to muscles contracting.

This contraction pulls the plasma membrane inward, pinching the cell into two. This inward puckering, or furrowing, continues to constrict until the membrane fuses, resulting in the cell being divided into two independent daughter cells, each with its own nucleus. This process ensures that the cytoplasm is evenly divided and is key to the successful continuation of life in multicellular organisms.

Cytokinesis Differences

Cytokinesis, while sharing the overarching goal of dividing the parent cell's cytoplasm to give rise to two daughter cells, differs significantly between plant and animal cells. The presence of a rigid cell wall in plants necessitates the formation of a cell plate to facilitate the separation. In contrast, animal cells, which lack a rigid wall, utilize the highly dynamic interactions between actin and myosin filaments to constrict the cell membrane, forming a cleavage furrow.

Additionally, the materials involved are distinct, with plant cells requiring the delivery of cell wall substances to build the cell plate, while animal cells rely on the contractile properties of their cytoskeletal elements. These differences underscore the evolutionary adaptations each cell type has made in order to efficiently accomplish the last step of cell division.

Cell Cytoplasm Division

The division of the cell cytoplasm, or cytokinesis, is a critical event that follows the end of mitosis. It ensures that each daughter cell not only obtains a complete set of chromosomes but also receives a fair share of the cytoplasm, including organelles and other cellular components.

In plants, this distribution occurs as the cell plate forms and expands to create two distinct cells. In animals, the cytoplasm is partitioned by the tightening of the cleavage furrow. Regardless of the method, proper cytoplasm division is crucial for the functionality and survival of the resulting daughter cells, as it provides them with the necessary components to sustain life and contribute to the growth and maintenance of the organism.