it says explain why the animal cells do not require a cell wall or a central vacuole for their functions
Animal cells do not require a cell wall or a central vacuole for their functions because they have evolved different mechanisms to fulfill the functions performed by these structures in plant cells.
1. Cell Wall: Plant cells have a rigid cell wall composed of cellulose, which provides structural support, protection, and prevents excessive water intake. In contrast, animal cells have a flexible outer membrane called the plasma membrane, which serves as a selectively permeable barrier between the cell and its environment. The plasma membrane is made up of lipids and proteins, enabling dynamic changes in shape and movement, allowing cells to carry out essential functions such as cell adhesion, communication, and transportation of molecules.
2. Central Vacuole: The central vacuole, found in plant cells, is a large fluid-filled organelle responsible for storing water, nutrients, and waste materials, maintaining cell turgor pressure, and playing a role in plant growth and development. Animal cells, on the other hand, have smaller, membrane-bound vesicles called vacuoles, which have specialized functions such as storing enzymes, hormones, and waste materials. Animal cells also possess lysosomes, which are membrane-bound organelles responsible for breaking down cellular waste materials and recycling cellular components.
Animals have evolved alternative mechanisms to maintain cell shape and structure, such as the cytoskeleton, which consists of microfilaments, microtubules, and intermediate filaments. The cytoskeleton provides mechanical support, enables cell movement, and assists in cell division.
In summary, animal cells do not require a cell wall or a central vacuole because they have substituted these structures with a flexible plasma membrane, smaller vesicles, and a cytoskeleton to fulfill their specific functions. These adaptations allow animal cells to perform essential activities related to cell structure, communication, and movement without the need for a rigid cell wall or a central vacuole.
Animal cells do not require a cell wall or a central vacuole for their functions for several reasons:
1. Structural Support: One of the primary functions of a cell wall in plant cells is to provide structural support and rigidity to the cell. Animal cells, on the other hand, rely on their cytoskeleton for support. The cytoskeleton is a network of protein filaments within the cell that helps maintain cell shape and provides structural support.
2. Flexibility: The absence of a cell wall in animal cells allows for greater flexibility and movement. Animal cells can change shape, migrate, and interact with other cells more easily compared to plant cells, which have a relatively rigid cell wall.
3. Cell-cell Communication: Animal cells rely on direct cell-to-cell contact and various cellular junctions, such as gap junctions and tight junctions, for communication and coordination. These junctions allow the exchange of signals, nutrients, and molecules between neighboring cells. Plant cells, on the other hand, use plasmodesmata, small channels through the cell wall, to facilitate communication.
4. Absorption and Excretion: In animals, cells are responsible for absorption and excretion processes. Since they lack a cell wall, animal cells can easily take up nutrients and eliminate waste materials through their flexible plasma membrane. Plant cells, with their rigid cell wall, perform these functions through specific channels and pores in the cell wall.
5. Osmoregulation: The central vacuole of plant cells plays a crucial role in regulating water balance and maintaining turgidity. Animal cells, however, regulate water balance through mechanisms such as osmosis and ion transport across the plasma membrane. They do not require a central vacuole for this purpose.
Overall, the absence of a cell wall and central vacuole in animal cells allows for greater flexibility, communication, and adaptability to changing environments. Animal cells have evolved different mechanisms to carry out their functions effectively without these structures.