Animation (with labels) of a plant cell, showing the structure and function of its vacuole (blue). Initially the view dives into the vacuole itself. The vacuole is a large, water-filled organelle within the cell. It is a critical structural element of the cell, and its high water pressure is part of what gives the cell, and the whole plant, its rigidity. The water in the vacuole contains numerous enzymes (blue, pink) that help to break down waste products. The view moves to a section of the vacuole's membrane, or tonoplast. This is a phospholipid bilayer, and contains numerous transmembrane channels called aquaporins (yellow). The control water flow into the vacuole, maintaining the cell's turgor. As the view moves outside the vacuole, water starts to leave the vacuole through the aquaporin cluster. This occurs for instance if the plant is placed in a saline environment. The vacuole shrinks, decreasing the volume of the cytoplasm and pulling the cell membrane (blue) away from the rigid cell wall (green). This is called plasmolysis, and causes the plant to lose rigidity and wilt. If the plant is placed in water again, it quickly refills the vacuole through its aquaporins, reinflating the cell. |