What is a central vacuole in a cell? Function, and Role

What is a central vacuole in a cell?

The central vacuole is a large vacuole found within plant cells. A vacuole is a sphere filled with liquid and molecules within a cell. The central vacuole stores water and maintains turgor pressure in a plant cell. It also pushes the contents of the cell to the cell membrane, allowing plant cells to absorb more light energy to produce food through photosynthesis. Vacuoles are also found in animal, protist, fungal, and bacterial cells, but large central vacuoles are only found in plant cells.

What is the function of a central vacuole?

The main function of the central vacuole is to maintain the turgor pressure in the cell. Turgor pressure is the pressure of the cell contents pushing against the cell wall; It is only found in cells that have cell walls, such as those of plants, fungi, and bacteria. Turgor pressure changes in a cell due to osmosis, which is the diffusion of water into or out of the cell. When a plant cell is in a hypotonic solution, there is a higher concentration of water molecules outside the cell than inside, and the water will flow into the cell. In plants, the vacuole fills with water and the cell is highly turgid. This is the optimal condition for plant cells.

Isotonic solutions have roughly the same concentration of water molecules inside and outside the cell membrane, so the amount of water going out and it is the same. Plant cells become flaccid in isotonic solutions and the plant can begin to sink. In hypertonic solutions, where there is more water inside the cell than outside, the water will drain out of the cell and the plant will wilt and possibly die.

The central vacuole is capable of storing a lot of water and swelling so that the plant cells can maintain the high turgor necessary for the optimal functioning of the plant. The central vacuole can also temporarily store wastes and nutrients, and their concentration also affects turgor pressure; having different water molecules in the central vacuole decreases turgor, so the cell must always have a much higher concentration of water in its central vacuole than any other molecule.

Plant cells thrive in hypotonic solutions because their cell walls prevent them from exploding due to excessive water consumption. In contrast, animal cells, which lack cell walls, do better in isotonic solutions. If the animal cells are in hypotonic solutions, too much water will enter the cell and the cell may burst.

The central vacuole can occupy 30-90% of the space of a plant cell within the cell membrane, and one of the other functions of the central vacuole is to push other cell contents closer to the cell membrane. This allows the organelles within the plant cell called chloroplasts to receive more light, which is very important because photosynthesis occurs in chloroplasts. Photosynthesis is the production of nutrients from light energy, carbon dioxide, and water; this is how a plant produces its food. By pushing chloroplasts closer to the cell surface, the central vacuole allows chloroplasts to absorb more energy from sunlight.

What are the 2 roles of the central vacuole in plant cells?

Storage of materials and support of the cell.

Central vacuole of plant cell

The central vacuole of plant cells is surrounded by a membrane called the tonoplast, an important and highly integrated component of the plant’s internal membrane network system (endomembrane). This large vacuole grows slowly as the cell matures by merging smaller vacuoles derived from the endoplasmic reticulum and the Golgi apparatus. Because the central vacuole is very selective in transporting materials across its membrane, the chemical palette of the vacuole solution (called cell sap) differs markedly from that of the surrounding cytoplasm.

For example, some vacuoles contain pigments that give certain flowers their characteristic colors. The central vacuole also contains plant debris that is bitter to insects and animals, while the cells of developing seeds use the central vacuole as a reservoir for protein storage.

Among its roles in the function of plant cells, the central vacuole stores salts, minerals, nutrients, proteins, pigments, helps plant growth, and plays an important structural role for the plant. Under optimal conditions, the vacuoles fill with water to the point of exerting significant pressure against the cell wall. This helps maintain the structural integrity of the plant, as well as the support of the cell wall and allows the plant cell to grow much larger without having to synthesize new cytoplasm. In most cases, the plant cytoplasm is confined to a thin layer placed between the plasma membrane and the tonoplast, resulting in an important relationship between the area of ​​the membrane and the cytoplasm.

The structural importance of the plant vacuole is related to its ability to control turgor pressure. Turgor pressure dictates the stiffness of the cell and is associated with the difference between the osmotic pressure inside and outside the cell. Osmotic pressure is the pressure required to prevent fluid from diffusing through a semi-permeable membrane that separates two solutions containing different concentrations of solute molecules. The response of plant cells to water is an excellent example of the importance of turgor pressure. When a plant receives enough water, the central vacuoles of its cells swell as fluid accumulates in them, creating a high level of turgor pressure, which helps maintain the plant’s structural integrity as well as support. of the cell wall. However, in the absence of sufficient water, the central vacuoles shrink and the turgor pressure is reduced, compromising the rigidity of the plant and causing wilting.

Plant vacuoles are also important for their role in molecular degradation and storage. Sometimes these functions are performed by different vacuoles in the same cell, one serving as a compartment for breaking down materials (similar to lysosomes found in animal cells) and another for storing nutrients, waste, or other substances. Several of the materials commonly stored in plant vacuoles are useful to humans, such as the scent of opium, rubber, and garlic, and are frequently harvested. Vacuoles also often store the pigments that give certain flowers their color, which helps them attract bees and other pollinators, but they can also release molecules that are toxic, odorous, or unpleasant to various insects and animals, discouraging them from consuming the plant. 

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What is a central vacuole in a cell? Function, and Role

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