Write a short note on vacuoles.

Vacuoles are present in both animal and plant cells. The contractile vacuoles of
protozoan enlarge by accumulating fluids and collapse by expelling them from
the cell. Vacuoles are particularly large and abundant in plant cells. These are
sap-filled vesicles in the cytoplasm, covered by a membrane called the
tonoplast. The vacuolar sap often contains minerals, sugars, amino acids,
proteins, esters, and water-soluble pigments, waste products in solution or as
crystalline deposits. The large vacuoles are formed by the union of smaller
vacuoles during the plants’ growth and development. Vacuoles serve as sites for
the storage of water and cell products or metabolic intermediaries.