Plant cells are made up of multiple organelles that work together to keep all aspects of the plant alive, and the central vacuole is one such organelle.
For example, you may have noticed a sort of water bubble that practically fills the whole cell when you examine plant cells with a microscope. The central vacuole is formed by this structure.
Yet, this plant organelle may perform a variety of important activities in addition to its structure. The vacuole’s job is also important. Below, we’ll go over each of them in depth.
Discovery of Vacuole
The first Scanning Electron Microscope was invented in 1935, and the discovery of the vacuole may be traced back to that. This organelle was thought to have no function until it was discovered that it contains little to no function (Latin: vacuus, “cell space devoid of any cytoplasmic substance”). However, throughout time, technological breakthroughs have significantly altered this notion.
Vacuoles were discovered by Antonie van Leeuwenhoek, the microscope’s inventor, in 1676. He was the discoverer not just of vacuoles, but also of numerous other cellular structures. He examined bacteria under a microscope for the first time. Other fascinating facts may be found in the history of microbiology.
What is the Central Vacuole?
All vacuoles of all types of cells were thought to have a similar origin. Different kinds and shapes of vacuoles, however, have been discovered in a wide range of cells by recent findings.
The presence of a large central vacuole, for example, which occupies a big portion of the cell mass and volume and is necessary for the physiology of the whole plant, is something that only plant cells have. Protein storage vacuoles and lytic vacuoles are the two types of plant vacuoles. Since they are transported by different transport vesicles, these two sorts represent different organelles.
Protein storage vacuoles are utilized to store different proteins, such as defense and storage proteins required for complete plant development.
- Lytic vacuoles, on the other hand, are mainly composed of hydrolytic enzymes that digest cellular components that are no longer, in any way, usable.
- Surprisingly, the desire to keep the roles distinct throughout embryonic development and maturation is shown by the separation of the function of protein storage vacuoles and lytic vacuoles. Both varieties, on the other hand, are anticipated to be a readily available source of different enzymes for germination.
Structure Of The Central Vacuole
The phospholipid bilayer forms the structural basis of the central vacuole, as well as other vacuoles. In most animal cells and other cell types, the vacuole is simply a tiny organelle; nevertheless, the vacuole seems to be the biggest organelle in practically 90% of all plant cell mass and volume. Compare plant cell division to animal cell division. For a thorough distinction between them, animal cells The cell sap and the tonoplast make up the central vacuole.
- Sugars, amino acids, lipids, and mineral salts are diluted in water to make up the cell sap, which is the liquid portion of the vacuole. The pigments that give the leaves and flowers their color are sometimes also included in this mixture.
- The tonoplast, on the other hand, is a membrane that separates the cell sap from the cell cytoplasm. The tonoplast literally means “tension” in Greek, and it helps provide the tension on the vacuole, which is true to its name. This vacuole membrane was named “tonoplast” by the Netherland botanist de Vries in 1885.
The membrane of the vacuole, like any biological membrane, contains a lot of transfer proteins that facilitate the movement of molecules into and out of it.
Watch this video to learn more about central vacuoles and other remarkable plant organelles.
Functions of the Central Vacuole in plants
There is a lot more to a vacuole than it seems, despite its simplicity. The central vacuole performs the following key roles in plant cells:
1. Maintain Turgor Pressure
The central vacuole may take up as much as 90% of the cell volume in a plant, as previously described. As a result, the turgor pressure, which is created by the cellular components to the cell wall, is maintained.
- The pressure that should be applied as a consequence of osmotic pressure is determined by the quantity of water inside the core vacuole. The central vacuole will expand when there are a lot of water molecules, producing greater turgor pressure, whereas it will shrink when there are few water molecules, producing lower turgor pressure.
2. Storage
The protein storage vacuole, which stores chemical products, is one kind of vacuole that has previously been mentioned.
- Plants like rhizomes, tubers, and bulbs are examples of plants that store a large amount of food material in the vacuole, which is a form of function that is very visible.
3. Defense
Plants have developed a defense cell death that would help them deter pathogens because they lack the so-called “immune cells.” The ways vacuoles are employed for defense are non-destructive and destructive, respectively.
- The enzymes required for cell death are discharged by a non-destructive process when the vacuolar membrane joins with the plasma membrane.
- The harmful process occurs when the vacuole membrane collapses, releasing the enzymes to immediately break down the cell contents; as a result, cells are killed right away.
4. Gas Exchange and Plant Locomotion
Vacuoles also control the rate at which plants breathe (gas exchange). The opening and closing of the stomatal pores in the leaves is controlled by special types of cells known as guard cells. The vacuoles of these guard cells are able to control this activity by regulating the absorption of water inside their membrane.
- Some plants, such as the Venus flytrap Dionaea muscipula and the delicate plant Mimosa pudica, use vacuoles to regulate their tonoplast activity and lose and absorb water during locomotion.
5. Cell Growth
The vacuole can assist during cell elongation by generating a high hydrostatic pressure inside the cell. When the cell wall gets soft and elastic enough for cell development, however, this happens.
- Furthermore, for better light exposure, the cell wall is pushed closer to the cytoplasmic organelles by the central vacuole.
Plants are often referred to as “inflatable” in general. What do you believe is the benefit of this structure, given your understanding of the central vacuole, and how such plant immobility compensation?