Vacuoles are membrane-bound sacs found within cells, primarily in plant and fungal cells. They serve various functions, including storing nutrients, waste products, and other substances. In plant cells, vacuoles are often large and help maintain turgor pressure, which keeps the plant upright and supports its structure. In addition to storage, vacuoles play a role in cellular processes such as maintaining pH balance and isolating harmful materials. They can also contain enzymes that break down waste products. Overall, vacuoles are essential for the proper functioning and health of cells, particularly in plants and fungi.