Vacuole



The vacuole is a large organelle found in prokaryotes and within the cytoplasm of eukaryotic cells. It frequently occupies the majority of the space inside plant cells where it typically exists as single transparent vesicle in mature cells, but small in some meristematic cells.

Like most organelles, the vacuole is membrane-bound compartment, and may function in a variety of systems such as digestion, secretion or excretion. In plants, it plays important roles in the storage of various products, by-products, nutrients and water. It is also used for sequestering unwanted debris, and toxic materials. In herbaceous plants it provides turgor pressure necessary for the structural support of soft tissues. Wilting in such plants is due to water loss within the vacuole.

Storage
Vacuoles serve as storage compartments for food, water, or other substances.

Contraction
Protists, organisms without cell walls, that live in hypotonic media (freshwater species), as the ciliate Paramecium, have contractile vacuoles, which periodically excrete fluid.

Pigmentation
Vacuoles are often pigmented, and the spectacular colors of petals and fruit reflect the presence of compounds such as the purple anthocyanins in the vacuole.