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Vacuoles Definition, Structure, Types, Functions, and Diagram

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Definition of Vacuoles

Vacuoles are membrane-bound organelle found in all fungal and plant cells as well as in some protist animal and bacteria cells. The most visible part of the majority of plants is a massive, fluid-filled vacuole. Large vacuoles can also be found in three filamentous genera of sulfur bacteria: Thioploca, Beggiatoa, and Thiomargarita. The function and significance of vacuoles differ significantly based on the type of cell, with a greater importance in cells of fungi, plants and some protists than they are in bacteria and animals.

There could be multiple vacuoles inside one cell. Each vacuole is separate from the cytoplasm via an individual unit membrane known as the tonoplast. In general, they comprise greater 30% of volume of cells however, this can vary between 5 and 90%, based on the type of cell.

Discovery of Vacuoles

  • The term “vacuole” was used by the renowned French scientist Félix Dujardin to refer to the empty space within the contractile vesicles of protozoa. Similar voids were also detected in the plant’s leaves and roots.
  • Therefore, plant scientists also adopted the phrase. In the first stages of vacuole study, microscopic imaging techniques and neutral-red staining suggested that the vacuole was an acidic environment surrounded by membranes.
  • By the close of the 19th century, de Vries hypothesized that tonoplasts, progenitors resembling plastids, generated vacuoles. Vacuole is an essential component of many cells.
  • Mature cells of all terrestrial plants, most fungi, and algae (excluding prokaryotic cells) have vacuoles. Nonetheless, animal cells and immature plant cells, as well as some very developed plant cells, lack vacuoles (such as stone cells).
  • Vacuoles account for up to 90 percent of the volume of mature plant cells. The biochemical investigation of this organelle was hampered for a long time by a lack of technology, and the majority of knowledge was derived from the research of yeast bubbles.
  • Yeast components were biochemically characterized and amino acid transport tests were conducted. The study of plant vacuoles was restricted to the location of a few vacuole components.
  • Early in the 1980s, the separation of vacuolar and purified vacuolar vesicles enabled biochemical and electrophysiological investigations of plant vacuolar transporters.

Structure of Vacuoles

  • They typically do not have a basic dimensions or shape; their structure is based on the demands for the particular cell.
  • In immature and active growing plant cells, the vacuoles are very tiny. The vacuoles first appear in the cells that are dividing young likely through the gradual formation of vesicles that originate of the Golgi apparatus.
  • A vacuole is enclosed by a membrane referred to as the vacuolar membrane, or tonoplast and is filled with cells’ sap.
  • The tonoplast is the cytoplasmic layer that surrounds a vacuole, which separates vacuolar contents from cell’s cytoplasm. As an organelle, it is mostly involved in controlling the movement of ions within the cell and isolating substances that could cause harm or danger on the body.
  • Vacuoles are structurally as well as functionally connected to lysosomes within animals and can have a range of hydrolytic enzymes. They also contain salts, sugars, nitrogenous compounds, like alkaloids and anthocyanin pigments that are found in cells’ sap.
  • The acidity of plant vacuoles could be up to 9 or 10 due to the large amount of alkaline substances , or as low as 3 . This is due to the accumulation of acid (e.g. tartaric, oxalic, and citric acids).

Types of Vacuoles

1. Sap Vacuoles/Central vacuoles

  • The sap vacuole is often referred by the name of central vacuole in the cell. It is one of the largest central organelles which make up much of the cell’s volume. The organelle is home to the liquid known as cell sap.
  • It is composed of various components, including sugars, water and amino acids, as well as other amino acids. When cells and plants develop, provacules that are part of the Golgi complex reassemble to create the sap vacuole in the inside in the cell.
  • Most mature plant cells include a single big vacuole that normally fills more than 30% of the cell’s volume and can occupy up to 80% of the cell’s volume under certain conditions. [23] Frequently, cytoplasmic filaments traverse the vacuole.
  • Vacuoles are wrapped by a membrane termed the tonoplast and filled with cell sap (etymology: Greek tón(os) + -o-, meaning “stretching”, “tension”, “tone” + comb. form repr. Gk plastós formed, molded).
  • Tonoplast is the cytoplasmic membrane encircling a vacuole, also known as the vacuolar membrane, which separates the vacuolar contents from the cell’s cytoplasm. As a membrane, its primary function is to regulate the passage of ions around the cell and to isolate potentially toxic or dangerous substances.
  • Transfer of protons from the cytosol to the vacuole stabilizes cytoplasmic pH while increasing the acidity of the vacuolar interior, so generating a proton motive force that the cell can use to move nutrients into or out of the vacuole.
  • The vacuole’s low pH also permits degradative enzymes to function. Although single big vacuoles are the most prevalent, the size and number of vacuoles can vary throughout tissues and developmental stages. For instance, growing cells of the meristems contain little provacuoles, but cells of the vascular cambium have numerous small vacuoles in the winter and one large one in the summer.
  • In addition to storing, the central vacuole’s primary function is to maintain turgor pressure against the cell wall. Aquaporins, which are present in the tonoplast, regulate the flow of water into and out of the vacuole by active transport, pumping potassium (K+) ions into the vacuolar interior.
  • Water will diffuse into the vacuole due to osmosis, putting pressure on the cell wall. If water loss causes a substantial decrease in turgor pressure, the cell will undergo plasmolysis. Turgor pressure generated by vacuoles is also necessary for cellular elongation: as the cell wall is partially destroyed by expansins, the less stiff wall is extended by pressure originating from within the vacuole.
  • The turgor pressure imposed by the vacuole is also necessary for the upright position of plants. Moreover, a central vacuole pushes all cytoplasmic contents against the cellular membrane, bringing the chloroplasts closer to the light source.
  • Most plants store compounds in vacuoles that interact with cytosolic molecules. If the cell is damaged, for instance by a herbivore, the two compounds can combine to generate poisonous chemicals. Alliin and alliinase are generally separated in garlic, but when the vacuole is ruptured, they combine to generate allicin. When onions are chopped, a similar process causes the creation of syn-propylthial-S-oxide.
  • Vacuoles in fungal cells fulfill activities similar to those in plant cells, and there can be several vacuoles per cell. In yeast cells, the vacuole (Vac7) is a dynamic structure capable of undergoing fast morphological changes.
  • They participate in numerous functions, including the maintenance of cell pH and ion concentration, osmoregulation, the storage of amino acids and polyphosphate, and degradative processes. To separate toxic ions from the rest of the cell, strontium (Sr2+), cobalt(II) (Co2+ ), and lead(II) (Pb2+) are carried into the vacuole.

Cell sap contents are transferred to the vacuole through the cytoplasm of the cell.


Other roles are:

  • Cell growth – Vacuoles aid in cell growth. vital in the plant cell due to the fact they assist in maintaining the the turgidity of cells. Vacuoles that are larger leads to growth or an increase in the dimensions of cells. This in turn contributes to the rigidity of tissue.
  • Storage – Other than the protein, vacuoles serve as storage containers for metabolites organic acids and sugars , among others.
  • Pigment deposition – VPigment deposition is a place in which pigments are deposited, permitting the use of vegetable colors such like blue, red and scarlet.

2. Contractile Vacuoles

  • Contractile vacuoles, also known as membrane bound organelles which are commonly found in kingdom protista (algae amoebas ciliates among others). In these cells the contractile vacuole becomes especially important because it assists in Osmoregulation (regulation of Osmotic pressure).
  • While the mechanism of entre is not fully identified, scientists suggest that the contractile vacuole complex (contractive vacuole complex) operates through the actions of two compartments connected by two distinct membranes.
  • The two membranes possess distinct characteristics that make it possible for the vacuole for the process of osmoregulation. This membrane is split into many tubules and vesicles, and is home to several proton-translocating VATPase enzymes. These enzymes are responsible for generating an electrochemical gradient protons . They also connect with the membrane of the second compartment.
  • The second compartment is the reservoir for storage of fluids and may also join to the membrane. It is, however, deficient in the V-ATPase enzymes, also known as holoenzymes. This is why it experiences periodic contraction, which allows the vacuole’s vacuole to release fluids. Together with other solvents the system functions as an engine that pumps out extra water every now and then time, preventing the cell from expanding and breaking.

Contractile Vacuoles are a specialized osmoregulatory organelle found in many protists with free-living cells. The contractile vacuole is a component of the complex contractile vacuole, which consists of radial arms and a spongiome. Periodically, the contractile vacuole complex contracts to remove excess water and ions from the cell in order to balance the water flow into the cell. When the contractile vacuole is slowly absorbing water, the contractile vacuole swells; this is known as diastole. When the contractile vacuole reaches its threshold, the central vacuole contracts regularly to release water.

Contractile vacuoles are protist cells’ specialized vacuoles. They are connected with the osmoregulation function. They remove extra water from the protist’s body since they tend to consume a lot of water. This is accomplished through contraction and ejection.

This procedure consists of two steps. The following are:

  1. When a protist’s contractile vacuole absorbs water, the vacuole swells and grows in size. This is known as the diastole phase.
  2. When the protists’ contractile vacuole achieves saturation/threshold, it begins contracting and expelling water in pulses. This is known as the systole phase.

3. Food Vacuoles:

  • Vacuoles that contain digesting enzymes are known as food vacuoles. Thus, they are also known as digesting vacuoles.
  • They have been observed in ciliates and sporozoans. Plasmodium falciparum, the malaria parasite, also possesses similar feeding vacuoles. Almost identical to lysosomes in their function.
  • These vacuoles are the places where the parasite digests the erythrocytes’ hemoglobin (Hb). When the development of anti-malarial medications began, this became the preferred target for scientists developing such drugs.

4. Air Vacuoles (Pseudo-vacuoles, Gas vacuoles)

  • Gas vesicles, also known as gas vacuoles, are nanocompartments that are gas-permeableand are found mostly in Cyanobacteria, as well as in other bacterial species and archaea.
  • Gas-filled vesicles allow bacteria to regulate their buoyancy. When little biconical structures expand to create spindles, they become spindles.
  • The vesicle walls are formed of a hydrophobic gas vesicle protein A (GvpA) that forms a hollow, cylinder-shaped, proteinaceous structure that is filled with gas.
  • Slight variations in the amino acid sequence alter the architecture of the gas vesicle; for instance, GvpC is a bigger protein due to these variations.
  • They’ve been observed exclusively in prokaryotes. The air vacuole isn’t an individual entity, nor it is protected by the same membrane.
  • It is composed of a range of smaller vesicles that are sub-microscopic. Each vesicle is protected by a protein-based membrane that protects the metabolic gases.
  • Air vacuoles don’t just contain gases, they also offer buoyancy, mechanical strength , and protection against harmful radiations.

5. Protein storage vacuoles (PSV)

Vacuoles that store proteins can be found in tissues that store proteins. Seeds are excellent examples of tissues in which proteins stored in reserve are stored. All proteins that are stored are synthesized first in the endoplasmic reticulum, which is transferred to the storage vacuole of proteins (PSV).

In certain plants, this procedure involves the movement of proteins via the autophagic process and also through proteins body (PBs). In contrast, the proteins can be removed through into the Golgi system (having already been produced by the ER) as prevacuoles prior to reaching the vacuole to be used to be stored.

In order for proteins to be successfully transferred through to the Golgi device to vacuole targeting is crucial. In this case, peptide-targeting sequences targets specific receptors on the vacuole. This allows proteins to be efficiently transferred and stored.

Based on the kind of plant, the storage tissues (seeds or seeds, for instance) are likely to contain a variety of well-packed storage vacuoles of protein. In addition according to the type of plant, there might be a variety of protein (sub-domains) that are stored.

6. Lytic vacuoles

Lytic vacuoles possess similar characteristics with lysosomes that are found in mammals. In addition, they have various kinds of hydrolytic enzymes that are which are responsible for the degradation of molecules such as nucleic acids polysaccharides and proteins.

Researchers have proposed that these organelles originate from the trans-Golgi nerve or are the result of dilation of a portion of the smooth endoplasmic retina.

Vacuoles of this type are also known as lytic compartments, and are identified by their optimal pH value of 5. Studies have revealed these vacuoles contain the following the oxidizing and hydrolytic enzymes:

  • Hydrolases – Fundamentally hydrolases are various kinds of hydrolytic enzymes which use water to break down chemical bonds. They can then break down bigger molecules down into smaller.
  • Esterases – Esterases include hydrolase enzymes which are specifically designed to degrade esters (compounds comprised of an acid and an alkyl group) into alcohols and acids.
  • Nucleases – Nucleases are enzymes responsible to break down bonds (phosphodiester bonds) in order to make nucleotides.
  • Peroxidases – Peroxidases peroxidases Peroxidases are enzymes that usually reduce hydrogen peroxide and taking it out of the chloroplast as well as the cytosol in addition to other parts of plants.

There are various processes by which cells get rid of old material as well as unwanted cytoplasm and the whole cell.

How Vacuoles are formed? – Formation Processes of Vacuoles

Vacuolar morphology was the only thing studied in the beginning phases of vacuolar study. However, advances in technology, including as metabolomics, proteomics, T-DNA insertion mutants, and heterologous complementation, have taken vacuole research to the molecular level in recent years.

How Vacuoles are formed? -  Formation Processes of Vacuoles
How Vacuoles are formed? – Formation Processes of Vacuoles
  1. Cell surface endocytosis leading to the prevacuolar region (PVC).
  2. The ER-to-late Golgi-to-secretory-compartment-transition pathway.
  3. A an early biosynthetic vacuolar route directs proteins to the PVC for storage. The Golgi complex and trans-Golgi network (TGN) play a crucial role in metabolic pathways.
  4. The late biosynthetic vacuole route  transports PVC to vacuoles.
  5. Degradation or biosynthetic routes bring PVC into vacuoles via autophagic vacuoles (AV).
  6. The ER to vacuole transport route is direct.
  7. Vacuole membrane ion and solute transport,.

Function of vacuoles

  • Specialized compartment: Vacuoles function as a specific chamber in which the cell disposes of all of its surplus supplies.
  • Storage of toxins: Vacuoles have a remarkable role in storing and thereby separating all of the cell’s waste products. This separation of poisons and hazardous ions protects the cell and other cell organelles from their harmful effects.
  • Maintenance of hydrostatic pressure: Vacuoles have a key role in the maintenance of hydrostatic pressure in eukaryotic plant cells, fungal cells, and some protist cells. The vacuole’s primary role is to maintain an internal hydrostatic/turgor pressure within mature plant cells. Due to the hydrostatic pressure of the central vacuole, this eventually contributes to the support and stature of plant components such as stems, leaves, and flowers. So, this effectively answers the question, what function does the vacuole serve in plant cells?
  • Storage: Vacuoles in plant cells also function as storage vesicles, particularly in plant seeds. Protein molecules are stored in protein bodies. These proteins are necessary for the germination of seeds and, consequently, the maintenance of plant life. Vacuole holds essential (nutrients-carbohydrates, lipids, and proteins) and non-essential (waste products, toxins) materials within the cell. It contains numerous digestive enzymes, tiny molecules, waste materials, ions, undesirable compounds, pigments such as anthocyanin, and so forth. When necessary, vacuole carries and releases materials within the cell. Example: Vacuoles of fat cells/adipocytes in animals contain lipid molecules. 
Protein bodies containing protein vacuoles.
Protein bodies containing protein vacuoles. Image Credit: Eliot M. Hermana.
  • Maintenance of pH: Vacuoles contribute to the proper pH maintenance in the cytoplasm of the cellular system. When the pH in the cell’s environment falls below the optimal level due to a random shift in the chemical gradient, protons (or H+ ions) begin to enter the cell from the outside environment. This increases the acidity of the cell and has severe consequences for the cellular system. Hence, the vacuole comes to the aid of the cell. The tonoplast or vacuolar membrane facilitates the movement of protons or H+ ions against the concentration gradient from the cytoplasm to the vacuole. Although this increases the acidity of the vacuole, it concurrently maintains the pH of the cell. 
You can notice the presence of Vacuolar Phosphate Transporters and V-ATPases on the “TONOPLAST/VACUOLAR MEMBRANE” that aid in the pH maintenance of cellular systems.
You can notice the presence of Vacuolar Phosphate Transporters and V-ATPases on the “TONOPLAST/VACUOLAR MEMBRANE” that aid in the pH maintenance of cellular systems. Image Credit: Bucher, M.,2016.
  • Growth: Uniquely, the central vacuole functions in plant cells during growth. They have the ability to develop enormously and allow the rapid growth of plant parts by utilizing only water. As a result, vacuole function in a plant cell is sometimes described as remarkable, as this phenomenon is not responsible for growth in animal cells. 
See how vacuoles aid in the exponential growth of plant cells. The plant hormone auxin stimulates this growth process in which plant cells absorb more and more water. Vacuole must eventually absorb all water and expand in order to survive. This expansion leads to the expansion, growth, and elongation of the cell.
See how vacuoles aid in the exponential growth of plant cells. The plant hormone auxin stimulates this growth process in which plant cells absorb more and more water. Vacuole must eventually absorb all water and expand in order to survive. This expansion leads to the expansion, growth, and elongation of the cell. Image Credit: Nagwa.
  • Autophagy: Vacuoles also serve a crucial function in autophagy.  They maintain a healthy equilibrium between the two conflicting biological processes, biogenesis and destruction. This is applicable to several substances, cell structures, misfolded proteins, invading microorganisms, etc. It is known that they store the byproducts of autophagy (age-related or damage-related).
  • Site of growth for some bacterial species: Salmonella can tolerate the acidic nature of vacuoles and multiply in the vacuoles of numerous mammalian animals after being ingested.
In the second row (ROW-B), the vacuole grows and finally ruptures, resulting in cell death. This is one of the several processes through which plant and animal cells undergo autophagy.
In the second row (ROW-B), the vacuole grows and finally ruptures, resulting in cell death. This is one of the several processes through which plant and animal cells undergo autophagy.

Development (Biogenesis of Vacuoles)

Vacuoles can be described as complex organelles, and the biogenesis of their formation is unexplored. Studies suggest that the vacuoles that are found at the tips of the root stem from vesicles arising out of Golgi body.

This process involves the combination of these vesicles in order to create prevacuoles that are precursors to vacuoles. It is the combination of these prevacuoles which eventually leads to the creation of the vacuole.

Role of vacuoles in Cell Defence and Cell Death

Vacuoles play a vital role in the defense as well as the death of cells.

While the mechanism isn’t still to be known vacuoles play a crucial role in the immunity of cells by releasing diverse substances (hydrolytic enzymes) and antimicrobes that kill the pathogen that invades. But, this mechanism has also been linked with the disease known as programmed cells dying (PCD).

In response to invaders within the cells, an enzyme referred to as vacuolar process enzyme causes the destruction of the vacuolar cell membrane, leading to the vacuole’s collapse in order to release hydrolytic enzymes as well as other antimicrobes. This causes not only the destruction of invaders but also the cell itself.

On the contrary, the fusion that occurs between the vacuole’s central part and the plasma membrane presence of the proteasome may result in the vacuole releasing antibacterial protease, as well as other vacuole components that may lead to the destruction of cells.

What is Central vacuoles?

The majority of mature plant cells contain one vacuole, which usually occupies more than 30 percent of the volume. It could be as large as 80percent of the volume for specific cells and types. Cellular cytoplasm is composed of many strands that typically traverse the vacuole.

A vacuole is enclosed by a membrane dubbed the tonoplast (word source from Gk ton(os) + -o-, which means “stretching”, “tension”, “tone” + comb. Form repr. Gk plastos is formed, form repr. Gk plastos,) and then filled with cells’ sap. Also known as the vacuolar lining and the tonoplast, it is the cytoplasmic membrane that surrounds the vacuole. It separates vacuolar contents from cell’s cytoplasm. As it’s a membrane, it’s mostly involved in controlling the flow of ions inside the cell and isolating any substances that may cause harm or danger on the body.

Protons are transported from the cytosol to vacuole can stabilize the pH of the cytoplasm, and makes the vacuolar interior more acidic, creating an electromotive force that cells can utilize to transfer nutrients into and from the vacuole. The lower pH of the vacuole permits degradative enzymes to function. While single vacuoles of a large size are the most frequent however the size and quantity of vacuoles could differ across various tissues and at different stages of development. For instance, the cells in development in the meristems have small provacuoles . Cells in the vascular cambium contain several small vacuoles throughout the winter months and a large one during summer.

In addition to storage, the most important function of the central vacuole is to keep pressure on the wall of cells. The tonoplast’s proteins (aquaporins) regulate the movement of water in the vacuole and out via active transport, pumping potassium (K+) ions through and out from the vacuolar interior. Because of osmosis, water diffuses into the vacuole, putting pressure on the cell’s walls. If the loss of water causes significant reduction in turgor pressure cell will begin to plasmolyze. The vacuole’s turgor pressure is also essential for cell extension. As the cell’s wall is partially destroyed by the action expansins, the less stiff wall expands due to the pressure exerted by the vacuole. The pressure of turgor generated by the vacuole is essential for supporting plants in a straight position. Another purpose of a central vacuole that it presses the entire components of the cell’s cytoplasm towards the cell’s membrane and keeps the chloroplasts nearer to sunlight. The majority of plants contain chemicals within the vacuole, which react with other chemicals in the cytosol. In the event that the cell gets damaged due to a herbivore, the two chemicals could react and create harmful chemical. For garlic, the alliin as well as the enzyme alliinase normally are separated , but they can form allicin when the vacuole has been broken. A similar reaction is responsible for the production of syn-propanethial-S-oxide when onions are cut. 

Vacuoles found in fungal cells carry out the same functions as plants. There may be multiple vacuoles for each cell. In yeast cells , the vacuole is a dynamic and flexible structure that can change its shape rapidly. They are involved in numerous aspects, such as the homeostasis of cell pH , amount of Ions, as well as osmoregulation, storage of amino acids, polyphosphate degradative and other processes. Toxic ions, like strontium (Sr2+), cobalt(II) (Co2+) as well as lead(II) (Pb2+) are carried into the vacuole in order to separate them from the cells.

What is Autophagy?

In plants autophagy is a crucial process that assists in the removal of undesirable substances from cells. There are various components within the cytoplasm that are no longer needed by the cell are contained inside a vesicle referred to as an autophagosome. These materials are transferred to the vacuole, in the vacuole, where they are degraded.

The expansion of the autophagosome’s double membrane can allow this vesicle , when closed, to keep cytoplasmic materials and components transported in the vacuole. The process also plays a role in the recycling of materials.

In the process of breaking down cell components into their essential components, which can be utilized by cells. As an example, breaking down of proteins results in peptides that can be later transported through the endoplasmic-reticulum and Golgi apparatus to process proteins.

Autophagy occurs in cells as a result of various circumstances within the cells, or as a result of things that affect the human body in general. For example, stressful circumstances as starvation can trigger the breakdown of different elements of the cell, such as proteins, lipids and even the lipids that are used to generate energy.

While it was thought that autophagy does not selectively eliminate certain cell components However, recent research has shown that this process can and does selectively eliminate certain components , such as proteins under certain conditions or in response to stressful conditions within yeast cells.

Structure and Function of Vacuoles in Animal Cells

  • Vacuoles are membrane-bound organelles found in animal cells, although they tend to be smaller and less conspicuous than those of plant cells. The structure and function of vacuoles in animal cells can vary based on the type of cell and the function they serve.
  • Contractile vacuoles are present in animal cells and are involved in osmoregulation and the elimination of excess water from the cell. These vacuoles are capable of filling with water and then contracting, expelling excess water and preserving the internal environment of the cell.
  • Animal cells also contain phagocytic vacuoles, which are generated when a cell ingests another cell or particle. The phagocytic vacuole combines with lysosomes, which contain enzymes that degrade the material ingested.
  • Vacuoles can also have a role in the storage of nutrients, such as glycogen or fat, in animal cells. When necessary, these vacuoles can provide the cell with a source of energy.
  • In addition to their unique functions, vacuoles in animal cells maintain the health and operation of the cell as a whole. They are able to regulate the interior environment, eliminate waste, and store vital nutrients.
  • While the shape and function of vacuoles in animal cells may differ from those in plant cells, vacuoles remain essential cell components that contribute to the health and function of the cell as a whole.
Structure and Function of Vacuoles in Animal Cells
Structure and Function of Vacuoles in Animal Cells. | Credit: MesserWoland and Szczepan1990 modified by smartse, CC BY-SA 3.0, via Wikimedia Commons

Structure and Function of Vacuoles in Plant Cells

In plant cells, vacuoles are membrane-bound organelles that serve critical functions such as cellular structure maintenance, environment regulation, and chemical storage and transit.

Structure and Function of Vacuoles in Plant Cells
Structure and Function of Vacuoles in Plant Cells. Credit: Mariana Ruiz LadyofHats, labels by Dake modified by smartse, Public domain, via Wikimedia Commons


  • Often found in plant cells, vacuoles are quite sizable and take up a lot of space. The tonoplast is the sole membrane that encloses these vacuoles and isolates them from the cytoplasm. Transporters help transfer molecules in and out of the vacuole, and lipids and proteins make up the tonoplast.
  • Water, ions, organic molecules, and occasionally colors or crystals make up the contents of the vacuole, often known as the cell sap. The vacuole can take up to 90% of the volume of some cells, such as the storage cells of seeds.


  • Storage: Many substances, including as water, ions, amino acids, carbohydrates, pigments, and toxins, are stored in vacuoles, the principal storage organelles in plant cells. Large molecules, including carbohydrates and amino acids, and waste materials that the cell wants to get rid of can be stored in these organelles.
  • Turgor Pressure: Vacuoles play a crucial role in preserving the form and stiffness of a cell, a process known as turgor pressure. They contribute to the formation of turgor pressure, the force exerted on the cell wall by the vacuole. This pressure keeps the cell from flattening out and keeps it in its present configuration.
  • pH regulation: Vacuoles also have a role in controlling the internal pH of the plant cell. Since an acidic pH is necessary for many enzyme activities, they can store protons and other ions.
  • Detoxification: Vacuoles can also be used for detoxification, storing and removing potentially hazardous substances that are made or taken into the cell.
  • Reproduction: Vacuoles are involved in reproduction in some plant cells. For instance, the vacuole is crucial in controlling the proportions of the pollen cell as it matures into a pollen grain.

In summary, the vacuole is an extremely important organelle in plant cells that serves many different functions that are vital to the health of the cell itself. It has many functions, including storage, shape maintenance, pH control, chemical detoxification, and participation in cell division and cellular reproduction.

Structure and Function of Vacuoles in Fungal cells

Typically, the vacuolar shape of fungal cells resembles that of animal cells. Yet, the functions of fungal vacuoles are comparable to those of plant vacuoles, as both fungal and plant cells lack lysosomes. The vacuoles of yeast cells (a type of fungus) conduct the following vital functions:

  • pH homeostasis of the cell
  • Ion enrichment and concentration
  • Osmoregulation
  • amino acid and polyphosphate storage
  • Degradation processes.
  • Storing hazardous ions such as strontium (Sr2+) and lead(II) (Pb2+).

Structure and Function of Vacuoles in Bacteria Cells

Although vacuoles are present in bacterial cells like they are in plant cells, the form and function of these vacuoles are very different.


  • By invaginating the cell membrane, bacteria create tiny spheres called vacuoles. The cytoplasm is where you’ll find them, enclosed by a single membrane. Vacuoles in bacteria can store a wide variety of substances, including gases, liquids, and nutrients.


Bacterial vacuoles serve different purposes depending on the kind of bacterium and the conditions in which they are found. Here are some of the things they do:

  • Nutrient storage: To ensure their continued existence and growth, bacteria need carbon and nitrogen, both of which can be stored in vacuoles. Bacteria can access the nutrients stored in vacuoles during times of food scarcity.
  • Wastewater management: Vacuoles are used by some bacteria involved in wastewater treatment to store waste products like ammonia, nitrogen, and other toxins. To protect the bacteria from the products, the vacuoles can secrete them outside of the cell.
  • Protection: Vacuoles provide some bacteria with a safe place to store water, allowing them to survive in hostile environments with high concentrations of salt. This aids in regulating the amount of water contained within the cell.
  • Gas storage: Certain bacteria are able to store gases in their vacuoles for usage when they are needed for metabolic operations; these gases include oxygen and nitrogen.

In conclusion, bacterial vacuoles are tiny organelles that perform crucial functions in the life and development of bacteria. They provide the bacteria with a safe haven from potentially harmful environmental conditions while also storing nutrients, waste products, gas, and other substances. The vacuoles in animal cells serve similar purposes to those in plant cells, but in distinct ways.

Structure and Function of Vacuoles in Protist Cells

Protists are a diverse group of single-celled organisms that can have a wide range of different structures and functions, including vacuoles. The structure and function of vacuoles in protist cells can vary depending on the type of protist.


The vacuoles in protist cells are similar in structure to those found in plant cells. They are membrane-bound organelles that are surrounded by a tonoplast membrane, which separates the contents of the vacuole from the cytoplasm. The size, shape, and number of vacuoles can vary depending on the type of protist.


The function of vacuoles in protist cells can vary widely depending on the type of protist and its environment. Some of their known functions are:

  1. Nutrient storage: Protist vacuoles can store nutrients, such as food particles and enzymes, that are required for the survival and growth of the cell. This is especially important for protists that live in nutrient-poor environments.
  2. Waste storage: Protist vacuoles can also store waste products, such as excess water, ions, and other molecules that need to be eliminated from the cell.
  3. Osmoregulation: In some protists, vacuoles play an important role in regulating the concentration of ions and other molecules inside the cell, which helps to maintain the proper balance of water inside the cell.
  4. Contractile vacuoles: Some protists have specialized vacuoles called contractile vacuoles, which are used to pump out excess water from the cell. This is important for protists that live in freshwater environments where water can easily flow into the cell.
  5. Gas exchange: Some protists use their vacuoles to exchange gases, such as oxygen and carbon dioxide, with the environment. This is important for protists that live in aquatic environments.

In conclusion, the vacuoles in protist cells can have a wide range of functions, including nutrient and waste storage, osmoregulation, gas exchange, and contractile vacuoles for water regulation. The specific function of vacuoles in protist cells can vary widely depending on the type of protist and its environment.


What is a vacuole?

A vacuole is a membrane-bound organelle found in cells that can store various substances, including water, enzymes, and waste products.

What is the function of a vacuole?

The function of a vacuole can vary depending on the type of cell and the organism it belongs to. Generally, vacuoles can store and regulate the concentrations of substances, such as ions and nutrients, within a cell. They can also play a role in cellular digestion, waste management, and cell growth.

What types of organisms have vacuoles?

Vacuoles are found in both plant and animal cells, as well as in many single-celled organisms.

How do vacuoles differ in plant and animal cells?

In plant cells, vacuoles are typically larger and more prominent than in animal cells. Plant vacuoles can occupy up to 90% of a cell’s volume and play a crucial role in maintaining the plant’s structure, turgor pressure, and nutrient storage. In animal cells, vacuoles are usually smaller and less prominent, and they may have different functions depending on the cell type.

Can vacuoles change in size and shape?

Yes, vacuoles can change in size and shape depending on the cell’s needs. For example, if a cell needs to store more water, the vacuole may expand to accommodate it.

How are vacuoles formed?

Vacuoles are formed from membrane vesicles that originate from the Golgi apparatus or the endoplasmic reticulum. These vesicles can fuse with existing vacuoles or with the plasma membrane to form new vacuoles.

What is the pH of a vacuole?

The pH of a vacuole can vary depending on the cell type and the function of the vacuole. For example, the vacuoles in plant cells can have an acidic pH to aid in the breakdown of proteins during digestion.

Can vacuoles be used for energy storage?

Yes, some vacuoles can be used for energy storage in the form of starch or other organic molecules. In plant cells, for example, the central vacuole can store starch for later use.

How do vacuoles contribute to the health of a cell?

Vacuoles play a crucial role in maintaining the overall health and function of a cell by regulating the internal environment, removing waste products, and storing essential nutrients.

Can vacuoles be targeted for medical purposes?

Yes, vacuoles have been targeted for medical purposes in various studies. For example, researchers have explored using drugs that target vacuoles to treat parasitic infections, cancer, and other diseases.


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