5 Facts On Food Vacuole In Protists (Formation, Function)

Food vacuoles are sac-like structures made up of single-layered membranes. These contain multiple enzymes to convert large molecules into smaller ones.

Food vacuoles in protists or other unicellular organisms are also called digestive vacuoles because they primarily do digestive functions. They are also involved in exocytosis and endocytosis, homeostasis and osmoregulation in both plant and animal cells.

These vacuoles encapsulate the food materials into vesicles and release the appropriate digestive enzymes to act upon these macromolecules and play a vital role in the breakdown of nutrients in most protozoans. Let us explore many more exciting facts related to food vacuoles, in this article.

Where are food vacuoles found in protists?

Besides protists, food vacuoles are also found in plants, fungi and other higher mammalian cells. Let us see where they are present inside a cell.

 Food vacuoles are found in the cytoplasm of a protistan cell. Amoeba is an organism with a unicellular structure having eucaryotic nuclei with 80’S ribosomal units. Sometimes, it is also known as the contractile vacuole in other organisms like paramecium.

The cytoplasm of protists is the matrix of the cell which is semi-fluid in nature and all other organelles embedded into it. Many functions like glycosylation and ATP production are performed in the cytoplasm. They are also well-designed sites for lipid production, the tricarboxylic acid cycle and the packaging of substances. This cytoplasm provides a better shape and size to the cell by using some protein fibres.

How are food vacuoles formed in protists?

Food vacuoles are involved in cellular digestion which is described as cell eating and cell drinking. Let us have a look at the formation of these vacuoles.

Food vacuoles arise from the fusion of phagosomes and pinosomes to form lysosomal vesicles. These vesicles arising from the Golgi are gradually fused to form these vacuoles via endocytic and biosynthetic pathways.

Food vacuoles are the storehouse of nutrients and other bioactive compounds like tannins, diterpenes, triterpenes, and some secondary metabolites etc. These are also involved in the exclusion of waste products passing away outside the cell.

Food vacuole functions in protists

Food vacuoles are dynamic organelles and can perform many more functions. Let us look at the main functions of these food vacuoles.

food vacuole in protists
Image credit: Picture showing how the food vacuoles are working inside a cell through phagocytosis by CNX OpenStax (CC BY 4.0)

The diverse functions of food vacuoles are listed below.

  1. Food vacuoles help in the digestion of biomolecules by cellular digestion, phagocytosis, or chemically induced mechanisms.
  2. Food vacuoles are involved in the detoxification and recycling of biological molecules as they perform homeostatic regulation of cytoplasmic ions and vacuolar biogenesis.
  3. Food vacuole protects the cell by self-toxicity and participates in cellular defence mechanisms by using hydrolytic enzymes against pathogens.
  4. Food vacuoles are also useful for maintaining the cell shape and size by reshaping the plasma membrane through storage, uptake, and excretion of multiple components and provide rigidity and stiffness to the cell.
  5. Food vesicles also play an important role in transporting solutes such as calcium, nitrogen and phosphorus compounds over long distances through fine channels by peristalsis.
  6. Food vesicles encapsulate food and break it down into simpler forms. When the food gets digested, nutrients and energy are stored in the cell itself and absorbed during cellular activities.
  7. Vacuolar ATPase, an enzyme plays a key role in the maintenance of electrochemical gradient throughout the membrane and also helps in pH regulation to balance the concentration of ions.

Food vacuole structure in protists

Vacuoles are categorised into four groups- Air vacuoles, Contractile vacuoles, Gas vacuoles and food vacuoles. Let us explore the structure behind these cellular components.

  • Food vacuoles are cellular compartments performing various functions like other cell organelles. These vacuoles vary in size, as they are not too large in animal cells due to the risk of disruption and are bounded by a single-layered membrane known as tonoplast.
  • Food vacuoles contain sap, digestive enzymes and a sufficient amount of water.
  • Plant cells have large vacuoles due to their water content. These vacuoles are associated with the vesicles produced from the endoplasmic reticulum filled with digestive enzymes poured by the lysosomes.
  • Before engulfing food materials, food vacuoles are smaller in size but after intake of materials, an increment in size is observed.
  • Most of the nutrients get absorbed by the surrounding matrix for assimilation while undigested components get ejected through the cytoproct (analogue to the anus). While in paramoecium, this is known as cytopyge.


In my conclusion, food vacuoles are circular portions that are not only a form of phagolysosome whose function is to degrade the components but also help in the transportation of molecules and ions from either side of the membrane.

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