vakuole

Vakuole, also called vacuole in English, is a membrane-bound organelle common in plant, fungal, and certain animal and protist cells. In plants, fungi, and many algae, the vacuole is large and central, bounded by a membrane called the tonoplast. In other cells, vacuoles are smaller and more numerous. Vacuoles originate from vesicles formed by the endoplasmic reticulum and Golgi apparatus and can change size by fusion with other vesicles or by water uptake.

Contents vary by organism and cell type. Plant central vacuoles typically store water, inorganic ions, and organic compounds; contain pigments and waste products; and help maintain turgor pressure essential for cell rigidity and growth. They also host hydrolytic enzymes and contribute to digestion and turnover in some organisms. In animal cells, analogous compartments are lysosomes or store substances; vacuoles can serve nutrient storage or transport roles.

Contractile vacuoles, found in some single-celled protists, expel excess water to regulate osmotic pressure. Pigment vacuoles store colored compounds such as anthocyanins in plants and algae. In fungi, vacuoles participate in storage and degradation, and may resemble lysosome-like vacuoles.

Overall, vacuoles perform osmoregulation, storage of ions, metabolites, and waste, degradation of macromolecules, and sequestration of toxic compounds. Their size and composition adapt to developmental stage and environmental conditions.