Purpose

A vacuole is any organelle with little or no internal structure.

Function

A vacuole is any membrane-bound organelle with little or no internal structure. It takes nothing from the cell, and produces nothing for the cell. It does, however, store things for the cell. In a sense, it is a "vacum". Though common in many cells, they are most prominent in plant cells, taking up most of the central space. Though the contents of the vacuole vary from organism to organism, as a rule, they contain:

atmospheric gases

inorganic salts

Organic acids

Sugars

Pigments

It is the pigments in the vacuoles that give flowers, such as this rose, their colors. In some plants, the vacuoles contain poisons. Biologists speculate that this is to help protect the plant from herbivores.

Location

In a plant cell, the vacuole is very prominent in the center, often shoving the other organelles up against the cell membrane. These water-filled organelles, along with the cell wall, help give the shell its structure, which allows for such phenomena as a thin-stemmed flower standing up straight.