Tuesday, January 22, 2013

Vacuole

A vacuole is a membrane bound organelle. Lets understand its structure and functions.

Structure:
Simple Diagram of a Vacuole
Do you know that there is a special name given to the membrane surrounding this vacuole? It is called the tonoplast. You might think that being a membrane-bound organelle, it might have a specific shape or size? The answer however, is no. There is no specific shape or size. It varies depending on the needs of the cell. For example, in a plant cell, there is generally one large vacuole at the center. In animals, there are small vacuoles but multiple in number. What does this vacuole contains? This vacuole does not take anything from the cell nor do it gives anything to the cell. It only stores nutrients for the cell. These are water-filled organelles containing various inorganic and organic molecules. It is also known to have contain wastes of the cell. Vacuoles can be central vacuole or food vacuole. The central vacuole is present only in plant cells which stores cell sap for the plant. It also allows for cell growth by absorbing water. Food vacuole is created by the process of endocytosis and is generally useful in storing food which is absorbed by the organism.
Why are these vacuoles present in the cell? What role do they play? Lets have a look at their functions.

Functions: 
The inside of the vacuoles contain water because of which there is pressure inside the cell called the turgor pressure (in plant cells) which gives structural support to the plants.It contains various inorganic and organic molecules of the cell which also includes enzymes in the solution. It stores wastes and exports these unwanted products from the cell. It also plays an important role in intracellular digestion and the release of cellular waste products.