Vacuoles are organelles that occupy 90% of the cells of plants and fungi, they make up a small sac that contains a cellular liquid, which is in charge of performing the various functions that keep the plant hydrated and healthy.
They are usually compared with the lysosomes of animals, due to their similarity in the functions they perform in terms of the digestive process. In addition, they are also responsible for destroying the cell that contains them when the natural process dictates it.
What is the function of vacuoles?
The cellular liquid that the vacuoles contain are an important part of the cell, because without them, the plant would not be able to process its food, or to discard everything that hurts it. That is, without the vacuoles, the plants could not stay alive. Among the other benefits to be gained from vacuoles are the following:
Store organic and inorganic compounds
Within this small sac are stored substances such as water, proteins, nutrients, minerals, digestive enzymes, and even bacteria that are good for the health of the plant. By containing all these substances, the vacuole ensures that the plant will be hydrated and with the necessary level of vitamins to develop and grow. Likewise, everything that the plant does not need is isolated and later discarded.
They contribute to osmosis
Osmosis consists of the entry and exit of the properties of water and minerals between cells, as well as between the external and internal environment. It is in the vacuole where this process takes place, keeping the cell and the plant hydrated.
They maintain the turgor of the cell
Carrying out the osmosis process, the vacuole fills with water, and it is at that moment that turgor arises. The vacuole is so filled with fluid that it tightens the cell walls, and this allows the plant to stand firm and rigid.
They expel waste from plants
The process of expelling waste, which in animals is known as excretion, in plants is carried out thanks to vacuoles, which absorb unnecessary molecules and expel them outside the plant. To carry out this process, the vacuole must move towards the cell wall and get rid of it, throwing it out of the cell.
Digestive enzymes, as well as the acid content of vacuoles, allow them to destroy and degrade the macromolecules that enter the cell. The membrane that covers it, the tonoplast, sends out ions that increase acidity and thus destroy them more efficiently.
They protect plants from toxic substances
Plants are often exposed to pesticides and insecticides, as well as polluting substances found in the air that, thanks to the functions of vacuoles, are not harmful to them. This happens by isolating the toxic substances and expelling them.
In addition, some vacuoles store chemical compounds that can be poisonous when released, in order to protect plants from animals that want to feed on them.
They give color to flowers and fruits
Cellular juice also contains numerous water-soluble pigments, which are responsible for giving color to the different parts of a plant. In this way, plants can change color in different weather seasons, and grow flowers of different colors, depending on the pigment that the vacuole contains. Likewise, fruits and vegetables owe their color to these pigments.
They take care of autolysis
Vacuoles have the function of destroying cells as a natural life process, and they do so by releasing digestive enzymes that are subsequently responsible for degrading the composition of the cell.
Structure of vacuoles
Its structure is really simple, taking into account the large number of functions it fulfills, which are quite complex. Vacuoles have a basic shape that is present in all cells, however, their content can vary from one to another.
Shape and size
These cellular organelles do not have a defined shape or size, as it varies with the maturity of the cell and the amount of water it absorbs. It consists of a single cell unit that is surrounded by a membrane called the tonoplast, with a characteristic that allows it to be permeable when needed.
According to the function that the plant fulfills, its physiological condition and that of the cell, it can vary in certain elements. However, there are components that will be present regardless of the type of cell or vacuole.
- Water: It is the main component, occupying most of the vacuole. Without it, plants do not survive.
- Carbohydrates: Like hemicellulose or starch, the latter is the most important staple food. They function as reserve foods.
- Proteins: They also function as reserve foods, the most common are glycoproteins, however, these will depend on the type of plant.
- Lipids: They are fats and oils, and they are important for the nutritional content of seeds and fruits. They also function as protectors for the exterior of the plant.
- Crystals: This is what food waste is called, although in many cases they are formed with the calcium in said waste, which is important for the development of the plant. The most common is oxalic acid.
- Sucrose: It fulfills an important function in the complex enzymatic system, produced thanks to photosynthesis. This component is what provides the sweet flavor to the fruits.
- Alkaloids and certain glycosides: They work as poisons to protect the plant from being eaten.
- Water-soluble pigments: According to the type of plant, they will give color to its parts.
Types of vacuoles
Depending on the type of plant and its role in the ecosystem, the type of vacuole will vary. The nutritional needs of the plant will also influence the types of vacuoles that develop.
This type of vacuole is responsible for expelling the excess water that may exist in it from the cell, which previously entered with the osmotic process. If this process is not carried out, the large amounts of water can weaken the cell, consuming the nutrients and proteins it needs to work properly.
They are responsible for keeping digestion working, absorbing nutrients and discarding toxins. This process is extremely important, because, otherwise, the plant can become intoxicated, cause irregularities in its functioning and eventually die.
The food vacuoles are formed from the cell membrane, nourishing the plant through the detoxification of substances, since there it obtains the calcium and other vitamins it needs to stay healthy.
Although vacuoles are mainly typical of plant organisms, there are some animal cells that contain them, they are usually called vesicles.
In these cases, they are much smaller with respect to the size of the plant vacuoles, but they perform practically the same functions, intervening in the protection against toxic substances that they can consume, as well as participating in the digestive and hydrating process.
Fun facts about vacuoles
In addition to all the functions performed by the different types of vacuoles with their different contents, there are some data that distinguish vacuoles in plant cells.
- Its name comes from a Latin word: vacuus , that is, empty. This is because, under the observation of a microscope, an apparently empty formation is seen, its contents cannot be observed.
- Cells are born with many vacuoles, which later, with the maturation process, unite until they become one.
- The membrane that protects it is composed of lipids, keeping salt water out, and allowing water to enter when needed.
- They are also present in the cells of fungi, and fulfill the same functions in them.
- They can represent 95% of the composition of a cell when they expand due to the large amount of water.
- They contain numerous ions.
- The cell juice absorbs the acidity of the cytoplasm and balances the PH of the plant.
Conclusion: Are vacuoles really important?
Vacuoles represent a very important part of plant cells and, therefore, of plants. The different liquid substances that this small bag contains carry out the nourishing and moisturizing processes that are needed so that a plant or fungus can stay alive in a healthy way.
In addition, in addition to the entire nutritional and digestive process in which they participate, these organelles collaborate in the protection of the plant through poisons, they are also the only ones that synthesize sucrose, a highly important component for the rest of living beings.
Dr. Samantha Robson ( CRN: 0510146-5) is a nutritionist and website content reviewer related to her area of expertise. With a postgraduate degree in Nutrition from The University of Arizona, she is a specialist in Sports Nutrition from Oxford University and is also a member of the International Society of Sports Nutrition.