Food vacuoles

A vacuole is a cell organelle found in a variety of cell types. Vacuoles are enclosed structures that contain fluid and are separated from the cytoplasm by a single membrane. They are mostly found in plant cells and fungi. Vacuoles are found in some protists, animal cells, and bacteria. Vacuoles are in charge of many important functions in a cell, such as nutrient storage, detoxification, and waste exportation.

What are Food vacuoles?

In cells, vacuoles are membrane-bound sacs. They are larger than the vesicle, their closest relative. When food comes into contact with the cellular membrane, small sacs form. The vacuole is frequently formed by the plasma membrane pinching off whatever needs to be destroyed. Our cells contain a wide variety of vacuoles, and the cells of other living creatures contain an even wider variety of vacuoles. These teeny-tiny sacs are extremely important.

Food vacuoles can be found only in the cells of plants, protists, fungi, and animals. Food vacuoles are circular portions of the plasma membrane that encircle food particles as they enter the cell. The food vacuoles are the mechanism by which a cell ‘eats,’ so that the food particles can be used as energy. They collaborate closely with lysosomes, which will be covered later in the lesson.

Food vacuoles formation

Food vacuoles form when food is pushed toward the cell’s membrane, which bends inward. When food pushes against the membrane, it stretches inward until the food particle is completely inside the cell, at which point the membrane pinches off, forming a vacuole. Phagocytosis is the term for this type of eating. Phagocytosis is the process by which smaller, single-celled organisms consume food. Imagine being able to wrap your arms around food and simply absorb it. This is similar to how a food vacuole functions.

Types of Vacuoles

Vacuoles of sap:

• It has a variety of transportation systems for the transportation of various substances. Animal cells and young plant cells both contain a number of small sap vacuoles. In mature plant cells, the small vacuoles fuse to form a single large central vacuole that takes up up to 90% of the cell’s volume.

• The cytoplasm is spread in the form of a thin peripheral layer by the large central vacuole.

• This is a device that allows for rapid exchange of cytoplasm with the surrounding environment. The fluid found in sap vacuoles is commonly referred to as sap or vacuolar sap.

Vacuoles Contractile:

• They are found mostly in freshwater protistan and algal cells.

• A contractile vacuole has a membrane that is highly extensible and collapsible. It’s also linked to a few feeding canals (e.g., Paramecium). Water, with or without waste products, is obtained by the feeding canals from the surrounding cytoplasm.            They pour it into the contractile vacuole.

• The vacuole expands. Diastole is the name given to this process. The swollen contractile vacuole collapses when it comes into contact with the plasma membrane. Systole is the term for collapsing. This expels the contents of the vacuole to the outside.

• Contractile vacuoles play an important role in osmoregulation and excretion.

Vacuoles for food:

• They are found in the cells of protozoan protists, several lower animals, and higher animal phagocytes.

• The fusion of a phagosome and a lysosome results in the formation of a food vacuole. The food vacuole contains digestive enzymes that aid in the digestion of nutrients. The digested materials are expelled into the cytoplasm.

Air vacuoles (also known as pseudo-vacuoles or gas vacuoles):

• They have only been found in prokaryotes.

• An air vacuole is not a single entity, nor is it surrounded by a single membrane. It is made up of many smaller sub-microscopic vesicles. Each vesicle is encased in a protein membrane and contains metabolic gases.

• Air vacuoles not only store gases, but also provide buoyancy, mechanical strength, and radiation protection.

Structure of Vacuoles

• They don’t have a fixed shape or size; their structure varies depending on the needs of the cell.

• The vacuoles in immature and actively dividing plant cells are quite small. These vacuoles form in young dividing cells, most likely through the progressive fusion of vesicles derived from the Golgi apparatus.

• A vacuole is surrounded by the tonoplast or vacuolar membrane and filled with cell sap.

• The tonoplast is the cytoplasmic membrane that surrounds a vacuole and separates its contents from the cytoplasm of the cell. As a membrane, it is primarily responsible for regulating the movement of ions within the cell and isolating materials that may be harmful or dangerous to the cell.

• Vacuoles are structurally and functionally similar to lysosomes in animal cells, and they may contain a variety of hydrolytic enzymes. In addition, sugars, salts, acids, and nitrogenous compounds such as alkaloids and anthocyanin pigments are commonly found in their cell sap.

• The pH of plant vacuoles can range from 9 to 10 due to the accumulation of alkaline substances or as low as 3 due to the accumulation of acids (e.g., citric, oxalic, and tartaric acid).

Conclusion

A vacuole is a cell organelle found in a variety of cell types. Food vacuoles can be found only in the cells of plants, protists, fungi, and animals. Food vacuoles are circular portions of the plasma membrane that encircle food particles as they enter the cell. The food vacuoles are the mechanism by which a cell ‘eats,’ so that the food particles can be used as energy. When food pushes against the membrane, it stretches inward until the food particle is completely inside the cell, at which point the membrane pinches off, forming a vacuole. In mature plant cells, the small vacuoles fuse to form a single large central vacuole that takes up up to 90% of the cell’s volume. The cytoplasm is spread in the form of a thin peripheral layer by the large central vacuole.