The Vacuoles Are multifunctional organelles found in the cells of all plants and fungi, as well as in some Protist cells , Animal and bacterial.
The term"vacuole"comes from the"Latin""vacuus"meaning"empty", since these are seen as an empty pocket when observed with a microscope .
In fact, vacuoles are small compartments in the cytoplasm of the cell. However, unlike the ones observed by the human eye, they are not empty, but contain chemicals and enzymes that allow the degradation of substances (such as food and toxic compounds ).
Vacuoles are responsible for a wide variety of functions, including nutrient storage, cell detoxification and waste export.
Characteristics of the vacuoles
1- Vacuoles are made mainly of water and amino acids. Also, fluids within the vacuoles include enzymes, sugars, mineral salts (potassium, sodium), oxygen, carbon dioxide and some pigments responsible for the coloration of the leaves of plants and flowers.
2- The vacuoles are surrounded by a layer of lipids, which allows to keep salt water out of the cytoplasm. This layer is called"tonoplast".
3 - Vacuoles are formed when the vesicles released by the endoplasmic reticulum And those released by the Golgi apparatus I are fused into a single organelle.
4- They are found mainly in the cells of plants and fungi. However, some animal, bacterial and protist cells have vacuoles.
5. Vacuoles are not of a specific size or shape. These two characteristics will depend on the individual needs of the cell.
6- The new cells contain a series of small vacuoles; However, when the cell matures, these small organelles fuse into a single central vacuole.
7- The central vacuole occupies 90% of the volume of the cell and can get to occupy 95% when it expands by the absorption of water.
8- Vacuoles in the plants fulfill functions similar to the Lysosomes In animal cells, since both are sacs containing digestive enzymes.
Functions of vacuoles
Vegetable eukaryotic cell.
Vacuoles fulfill a wide variety of functions within the cell. Among the main functions are:
1- Regulating the osmotic properties of the cell
Osmosis is a phenomenon that refers to the passage of a liquid through a semipermeable membrane, as in cells, whose membranes allow the passage of water and other substances.
It should be noted that vacuoles regulate the passage of these substances, retaining what they consider harmful and metabolizing others.
2- Storing substances
Vacuoles can store various substances that are essential for cells, such as food, water, ions, minerals, nutrients, enzymes, plant pigments and bacteria beneficial to the cell.
Likewise, vacuoles can store cell debris, as well as isolate materials that can be harmful.
3- Help maintain the pressure inside the cell (turgor)
The Turgor Is a phenomenon that occurs when the cell swells due to the force exerted by the internal fluids.
This phenomenon generates an excess of pressure on the cell wall. Vacuoles release part of this pressure by using water (hydrostatic pressure), which helps maintain cell and plant rigidity.
4- Maintaining the pH balance inside the cell
The vacuole absorbs the acidity of the cytoplasm of the cell.
5- Exporting products outside the cell
Unlike animals, plants do not have a system of excretion proper, so it depends on other methods to expel waste and toxic substances.
The cell uses the vacuole to get rid of molecules it does not need. To accomplish this, the vacuole absorbs the unwanted element and subsequently moves towards the cell wall.
Once in the cell wall, the vacuole fuses with this, opens and expels the"garbage". This organelle is then closed and separated from the cell wall,
6- Molecular degradation
The acid environment inside the vacuoles as well as the enzymes present in this organelle help to degrade large molecules that are sent to the vacuoles.
The tonoplast intervenes by transporting hydrogen ions from the cytoplasm to the vacuole, which increases the acidity of the environment. In this sense, vacuoles resemble lysosomes in animal cells.
7- Detoxification
Vacuoles protect the cytosol from toxic substances, such as heavy metals and herbicides.
8- Protection
Some vacuoles store and release chemicals that are poisonous or have a bad taste. These chemicals keep predators away from the body.
9- Seed germination
Vacuoles are the source of the nutrients required by the seeds during germination, since these organelles store the carbohydrates, proteins and lipids necessary for growth.
10- Autolysis
Vacuoles intervene in the programmed death of a cell, which occurs through a process called"autolysis"(from the Greek self,"to itself", and lysis,"loss."This is a natural process in which The cell is destroyed by its own enzymes.
The tonoplast surrounding the vacuole is broken by releasing the substances it stores; Subsequently, the digestive enzymes of the vacuole degrade the cell.
Vacuoles also intervene in other activities of the cell, such as:
1- The Autophagy , (From the Greek self,"to itself", and phagia,"to eat") which is a process by which part of the cytoplasm of the cell are absorbed by the vacuoles for their decomposition.
2 - The biogenesis , Production of living beings from other living beings.
References
1. What is a Vacuole? Retrieved on May 24, 2017, from quatr.us.
2. Vacuole Organelle. Retrieved on May 24, 2017, from thoughtco.com.
3. Function of the Vacuole. Retrieved on May 24, 2017, from softschools.com.
4. What are vacuoles made of? What are its functions? Retrieved on May 24, 2017, from quora.com.
5. Vacuole (plants). Retrieved on May 24, 2017, from bscb.org.
6. Vacuole. Retrieved on May 24, 2017, from britannica.com.
7. Plant vacuole. Retrieved on May 24, 2017, from nature.com.