• Explain why animal cells do not require a cell wall or a central vacuole.
Animal cells do not require a cell wall or a central vacuole because their survival and functionality rely on different structures and mechanisms compared to plant cells.
1. Structural support: Plant cells have a rigid cell wall made of cellulose, which provides strength and support to the cell. This is important for maintaining the shape and structure of plant tissues. On the other hand, animal cells do not have a cell wall. Instead, they have a flexible plasma membrane that allows for movement and shape changes. The absence of a cell wall allows animal cells to be more dynamic and versatile.
2. Mobility: Animal cells are often specialized for locomotion and movement. They need to be flexible and able to change shape easily. The absence of a cell wall allows for more freedom of movement and adaptability. Animal cells achieve this mobility through structures such as cilia, flagella, and muscle fibers, which plant cells lack.
3. Nutrient storage and regulation: In plant cells, the central vacuole serves several functions like storing water, nutrients, and waste products, along with maintaining cell turgor pressure. However, animal cells have smaller and numerous vacuoles that function mainly for storing and transferring materials. Instead of a central vacuole, animal cells utilize other organelles like lysosomes, peroxisomes, and vesicles to store and transport materials, metabolites, and waste products.
4. Osmoregulation: In plant cells, the central vacuole plays a crucial role in osmoregulation by controlling the water balance within the cell. The vacuole absorbs water, creating turgor pressure that helps maintain cell shape and supports the plant. In contrast, animal cells rely on processes such as active transport and ion channels embedded in the plasma membrane to regulate osmotic balance and maintain proper hydration.
Overall, animal cells have evolved different mechanisms, such as a flexible plasma membrane and specialized organelles, to fulfill their unique physiological needs. The absence of a cell wall and central vacuole allows animal cells to be more adaptable and mobile, characteristics necessary for their survival and various functions in animal tissues and organs.