# Vacuoles: Definition, Structure, Types, Functions, and Cell Differences

> Learn what vacuoles are, their structure and major types, how they function in cells, and how vacuoles differ across plant, fungal, protist, and animal cells.

Canonical URL: https://biologynotesonline.com/vacuoles-types-structure-and-functions/
Author: Sourav Pan
Last updated: September 9, 2026

![Vacuoles: Definition, Structure, Types, Functions, and Cell Differences](https://biologynotesonline.com/wp-content/uploads/2023/11/Vacuoles-Definition-Structure-Types-Functions-and-Diagram-scaled-1.jpg)

Vacuoles are membrane-bound, fluid-filled compartments present in different eukaryotic cells. They are generally larger than ordinary transport vesicles and their size, contents and functions can vary greatly with the cell. 

Vacuoles are especially prominent in plant and fungal cells, where one or several large vacuoles may occupy a considerable part of the cell volume. In plant cells, the membrane surrounding the vacuole is called the tonoplast, and a large central vacuole may occupy most of a mature cell. Many protists also contain well-developed vacuolar compartments which take part in storage, digestion and regulation of water or ions. 

The term needs more qualification in animal cells. A typical animal cell does not contain the large vacuole characteristic of plants and fungi, and similar membrane-bound compartments are more commonly referred to as lysosomes, endosomes, phagosomes or vesicles according to their function. However, prominent vacuolar structures can occur in some specialized animal cells.

Vacuoles, vesicles and lysosomes are membrane-bound structures found within the eukaryotic cells. They are not the same. Vesicles are generally small membrane-bound sacs, which are used to carry proteins, lipids and other materials from one cellular compartment to another. 

Vacuoles are larger compartments. In plant and fungal cells, they are used for storage, degradation and different other cellular functions. 

Some vacuoles, especially those structurally related to [lysosomes](https://biologynotesonline.com/lysosome/), contain degradative enzymes used to break down cellular materials. Lysosomes are acidic membrane-bound organelles having hydrolytic enzymes, which take part in breakdown of cellular and extracellular materials. Some vacuoles can perform this lysosome-like degradation, along with other functions also.

## Where Vacuoles Are Found?

The following are the major cells in which vacuoles are found-

- Plant cells- Vacuoles are very prominent in plant cells. In many mature plant cells, one large central vacuole is present and it can occupy a major part of the cell volume. Different plant cells can also contain vacuoles of different size and type.

- Fungal cells- Most fungal cells (including yeasts) contain one or several vacuoles. These may form large fluid-filled compartments within the cell.

- Protist cells- Vacuoles are also found in many protists. Contractile vacuoles are particularly common among freshwater and soil-dwelling protists, where they collect and expel excess water. Their occurrence and structure varies between different protist groups.

- Algal cells- Vacuolar compartments occur in algae also. They are well developed in many algal cells, including green algae.

- Animal cells- The large and persistent vacuole typical of many mature plant cells is generally not present in animal cells. Comparable acidic and degradative compartments are mainly described as lysosomes and endosomes.

## Structure of Vacuoles

![Plant cell with a large central vacuole and magnified tonoplast showing V-ATPase, V-PPase, TIPs, ion transporters, cell sap, and proton movement.](https://biologynotesonline.com/wp-content/uploads/2024/04/Structure-of-a-Plant-Vacuole-and-Tonoplast-1024x725.webp)Plant cell with a large central vacuole and magnified tonoplast showing V-ATPase, V-PPase, TIPs, ion transporters, cell sap, and proton movement.

- Vacuolar membrane (Tonoplast)- The vacuole is bounded by a single membrane. In plant cells, this membrane is known as tonoplast. It forms the outer covering of vacuole and separates the vacuolar content from surrounding cytoplasm.

- Vacuolar lumen- Inside the tonoplast, a fluid-filled space is present which forms the lumen of vacuole. In plant cells, the fluid present in it is commonly called cell sap. It contains water along with different dissolved substances.

- Proteins of tonoplast- Several proteins are located in the tonoplast. These include proton pumps, ion channels, transporters and tonoplast intrinsic proteins (TIPs). V-ATPase and V-PPase are involved in movement of H⁺ into the lumen. Due to this, the internal region becomes acidic. Different ions and other substances are also moved through specific channels and carriers.

- Contents of vacuole- Vacuolar content is not the same in all cells. Mineral ions, sugars, amino acids, organic acids, pigments, proteins and different secondary metabolites may be present in it. Some vacuoles contain hydrolytic enzymes also.

- Size and shape- Vacuoles show variation in number, size and shape. A mature plant cell generally has one large central vacuole. It may occupy most of the intracellular region, whereas several smaller vacuoles can occur in other cells.

## Types of Vacuoles

![Comparison of central, lytic, protein storage, food, and contractile vacuoles with bacterial gas vesicles shown as protein-shell buoyancy structures.](https://biologynotesonline.com/wp-content/uploads/2024/04/Types-of-Vacuoles-in-Plants-Protists-and-Microorganisms-1024x576.png)Comparison of central, lytic, protein storage, food, and contractile vacuoles with bacterial gas vesicles shown as protein-shell buoyancy structures.

The following are some of the important types of vacuoles-

- Central or Sap Vacuole- It is a large vacuole mainly found in the mature plant cells. In some cells, it may occupy up to 90% of the total cell volume. The vacuole contains cell sap, made up of water, ions, sugars, organic acids, pigments and other metabolites. It is used for storage and maintaining the [turgor pressure](https://biologynotesonline.com/turgor-pressure/). Cellular homeostasis is also maintained with the help of this vacuole.

- Lytic Vacuole (LV)- These are the degradative vacuoles present in plant cells. Different hydrolytic enzymes are present inside it which break down the unwanted cellular materials. It also takes part in recycling and storage of ions.

- Protein Storage Vacuole (PSV)- Protein storage vacuoles are mainly present in the seed cells. Large amount of storage proteins and some defense proteins are accumulated in these vacuoles. During seed germination, these stored proteins are broken down and used by the developing embryo.

- Food Vacuole- It is a digestive type of vacuole found in many protists. Food particles after entering the cell are enclosed inside the food vacuole. Digestion then takes place with the help of digestive enzymes. In [Paramecium](https://biologynotesonline.com/paramecium-cell/), the food entering through the oral groove forms food vacuoles. The undigested substances are later removed out from the cell.

- Contractile Vacuole- This type of vacuole is commonly found in freshwater protists and is used to maintain [osmotic balance](https://biologynotesonline.com/osmoregulation-definition-types-mechanism-importance/). Excess water entering inside the cell is collected by the contractile vacuole. After filling, the water is periodically expelled outside. This prevents excessive swelling of the cell.

- Gas Vacuoles- Gas vacuoles are found in some aquatic bacteria and archaea, including several cyanobacteria. These are different from the fluid-filled membrane bound vacuoles of eukaryotic cells. Gas vacuoles consist of groups of hollow protein structures called gas vesicles. It provides buoyancy to the microorganisms and helps them to maintain a favourable position in the water column.

## Formation of Vacuoles

Vacuole formation is not based on a single pathway. In plant cells, different parts of the endomembrane system take part during its formation.

![Plant vacuole formation showing ER and Golgi/TGN trafficking, prevacuolar compartments, provacuoles, membrane fusion, enlargement, and formation of the central vacuole.](https://biologynotesonline.com/wp-content/uploads/2024/04/Formation-of-the-Plant-Central-Vacuole-1024x576.webp)Plant vacuole formation showing ER and Golgi/TGN trafficking, prevacuolar compartments, provacuoles, membrane fusion, enlargement, and formation of the central vacuole.

- [Endoplasmic reticulum (ER)](https://biologynotesonline.com/endoplasmic-reticulum/)- The formation begins with membranes and vacuolar proteins associated with the ER. Some newly forming provacuolar membranes can arise directly from the ER.

- Golgi and TGN pathway- Many vacuolar proteins pass through the [Golgi apparatus](https://biologynotesonline.com/golgi-apparatus/) and trans-Golgi network (TGN). In this step, the materials are sorted for further transport towards vacuolar compartments.

- Prevacuolar compartments- Transported materials reach prevacuolar compartments (PVCs) or multivesicular bodies (MVBs). These compartments are involved during delivery of cargo to the developing vacuole.

- Provacuole formation- Small vacuolar structures or provacuoles are formed. They can occur as tubular or small membrane-bound compartments in young cells. Different routes may take part in their formation.

- Fusion and enlargement- The small vacuolar compartments fuse with each other. During this process, the vacuoles become larger and their membrane (tonoplast) is continuously developed.

- Central vacuole formation- Further fusion and expansion finally produces the large central vacuole characteristic of many mature plant cells. Vacuoles can also develop by remodeling or inheritance of already existing vacuolar compartments, so their formation is not same in every cell.

## Functions of Vacuoles

![Plant cell mechanism showing vacuolar solute accumulation, water entry, central vacuole expansion, and turgor pressure against the cell wall.](https://biologynotesonline.com/wp-content/uploads/2024/04/Central-Vacuole-Turgor-Pressure-and-Plant-Cell-Expansion-1024x576.webp)Plant cell mechanism showing vacuolar solute accumulation, water entry, central vacuole expansion, and turgor pressure against the cell wall.

- Storage of materials- Vacuoles are used to store water, inorganic ions, sugars, organic acids, proteins, pigments and different metabolites. Toxic substances and xenobiotics can also be accumulated inside it.

- Maintenance of turgor pressure- In plant cells, the central vacuole maintains turgor by accumulation of water and solutes. This provides mechanical support to the cell and also takes part during cell expansion.

- Cellular homeostasis- It helps in regulation of cytoplasmic pH and proper balance of different ions and metabolites.

- Degradation of cellular materials- Lytic vacuoles contain hydrolytic enzymes which break down unwanted cellular substances. Thus, it performs a degradative function in the plant cell.

- Osmoregulation- Contractile vacuoles of many freshwater protists collect excess water entering inside the cell. The water is then expelled outside periodically, maintaining the water balance of cell.

- Digestion of food- Food vacuoles are involved in intracellular digestion in many protists. Food particles are enclosed in it and broken down with the help of digestive enzymes.

- Defense- Different defensive compounds can be stored inside plant vacuoles. These compounds along with vacuolar proteins also take part during defense against pathogens and herbivores.

- Buoyancy- In gas-vacuolate bacteria and archaea, groups of gas vesicles provide buoyancy. It helps the cell to maintain a suitable position in the water column.

## Vacuoles in Plant and Animal Cells

The major differences between vacuoles of [plant and animal cells](https://biologynotesonline.com/plant-cell) are as follows-

FeaturesPlant CellsAnimal CellsSize and prominenceVacuoles are generally large and prominent, especially in mature plant cells. Their size, however, changes with cell type, developmental stage and conditions.Vacuolar compartments are usually much smaller and less prominent. Some specialized animal cells can also develop large vacuolar structures.NumberA single large vacuole is commonly found in mature vegetative cells. But this is not fixed. Several small or functionally different vacuoles may also be present in the same cell.Usually several small vacuolar or lysosomal compartments are present rather than one dominant vacuole. Their number and form can vary considerably between cell types.Typical cellular rolesIt is used for storage, maintenance of ion and pH balance, turgor and degradation of cellular materials.Vacuole-like compartments mainly take part in intracellular digestion and endocytic processes. Storage and transport are commonly carried out through different membrane-bound vesicular compartments.Central vacuoleA large central vacuole is characteristic of many mature plant cells and can occupy most of the cell volume.A comparable permanent central vacuole is generally absent in typical animal cells.TurgorThe central vacuole has an important role in maintaining turgor pressure. Water entering the vacuole also supports cell enlargement.Plant-like turgor maintenance is not its usual function. Animal cells lack the rigid cell wall against which this pressure acts.StorageVacuoles store ions, sugars, organic acids, proteins, pigments and several other metabolites. Protein storage vacuoles (PSVs) are particularly important in seeds.Storage is comparatively less associated with a single vacuolar organelle. Different vesicles and related endomembrane compartments perform such functions.DegradationLytic vacuoles (LVs) contain hydrolytic enzymes and break down unwanted cellular materials.Degradation is mainly carried out by lysosomes, which contain different hydrolytic enzymes.Relevant terminologyCommon terms include central vacuole, lytic vacuole (LV), protein storage vacuole (PSV) and tonoplast for the vacuolar membrane.Lysosome and endosome are more commonly used for related animal endomembrane compartments. The term vacuole is also used in animals, but not as one uniform equivalent of the plant central vacuole.

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