vakuol

Vakuol, also known as vacuole, is a membrane-bound organelle found in many eukaryotic cells. Its size, number, and importance vary among organisms: plant and fungal cells typically contain large central or specialized vacuoles, while animal cells often have smaller, more numerous vacuoles.

Vacuoles are formed from components of the endomembrane system, including vesicles budding from the endoplasmic reticulum and Golgi apparatus. The vacuolar membrane, called the tonoplast in plants and many fungi, encloses the vacuolar lumen. The interior is usually acidic and can contain enzymes such as hydrolases, depending on the vacuole’s role. In protozoa, contractile vacuoles regulate water balance and can expel excess liquid.

Functions of vacuoles are diverse and adapted to the organism. They store water, ions, sugars, organic acids, pigments, and waste products. In plant cells, the central vacuole maintains turgor pressure, supporting cell rigidity and growth. Vacuoles also serve in digestion, with lytic vacuoles containing degradative enzymes analogous to lysosomes in animal cells. Some vacuoles sequester toxic compounds or secondary metabolites, contributing to pigment storage and protection from herbivores. In certain protists, contractile vacuoles actively manage osmotic stress.

Common vacuole types include the central vacuole of plant cells, lytic vacuoles in fungi and some protists, and pigment or storage vacuoles across various tissues. The term vacuole reflects their versatile, often expansive role in cellular physiology, ranging from structural support to metabolism and detoxification.