WHAT IS INTRACELLULAR DIGESTION? - BIOLOGY - 2025

The digestion intracellular is the process by which cells use their enzymatic machinery for degrading molecules within the same cell. The principle of intracellular digestion is very similar in various organisms.

Once the compound to be digested (commonly a food source) has entered the cell, it is located in a vacuole. Subsequently, hydrolytic enzymes enter the interior of the vacuoles, degrading the compound.

Intracellular digestion process. 1) Foreign body to the cell, 2) Vacuole, 3) Lysosomes, 4) Cell.

The enzymes responsible for intracellular digestion are produced mainly by lysosomes. Some of the most important hydrolytic enzymes in intracellular digestion that have been reported are acid phosphatase, ATPase, 3r-AMPase and E600-resistant esterase, among others.

What organisms carry out intracellular digestion?

Source: docplayer.es

Both unicellular and multicellular organisms carry out intracellular digestion processes.

Some authors assume intracellular digestion as an exclusive process of heterotrophic organisms. However, many other authors recognize some degradation processes that occur in plants such as intracellular digestion.

At the end of the intracellular digestion processes, some elements remain that were not degraded by the enzymes. These elements are promptly expelled out of the cell by means of vacuoles.

Phagocytosis and extracellular digestion

Phagocytosis consists of a process by which cells surround some large particles with their membrane, that is, they enclose them in vacuoles within them. Later the lysosome provides the necessary enzymes to digest the phagocytosed element.

The phagocytosis process occurs partly in the circulation and partly in fixed tissues. Cells in the circulation known as macrophages and microphages are responsible for phagocytosis in the circulation.

In fixed tissues, the most common is to find only macrophages similar to those of the circulatory system. Phagocytosis commonly occurs in fixed tissues such as endothelium and connective tissues.

Intracellular digestion in different organisms

In mammals, the molecules to be degraded are concentrated in digestive vacuoles. Later, small lysosomes from the Golgi apparatus reach the vacuoles, carrying the hydrolytic enzymes necessary for the process.

Once the molecules are fragmented, they are absorbed into the cytoplasm and serve as nutrients.

In humans in particular, it has been observed that cells responsible for immunological processes, known as leukocytes, can intracellularly phagocytose and digest some bacteria that attack the body.

In some mollusks such as clams and oysters, food sources are processed relatively slowly through intracellular digestion. This occurs through a glandular route of the digestive gland.

Plants also develop vacuoles in which intracellular digestion processes of compounds such as proteins occur.

Although they present some differences with the intracellular digestion of animals, the process is very similar, since the vacuoles of plants have properties similar to those of animal lysosomes.

In other unicellular organisms, intracellular digestion processes are also known to degrade molecules such as proteins.

These digestion processes in organisms such as bacteria and fungi have many characteristics in common with those described in the case of mammals.

References

1. Decho A. Samuel N. Flexible Digestion Strategies and Trace Metal Assimilation in Marine Bivalves. Limnology and Oceanography. nineteen ninety six; 41 (3): 568-572
2. Douglas S. An Experimental Investigation into the Role of the Blood Fluids in the Intracellular Digestion of Certain Bacteria and Red Blood. Proceedings of the Royal Society of London. 1916; 89 (617): 335-341
3. Goldberg A. Dice J. Intracellular protein degradation in Mammalian and Bacterial Cells. Annual Review of Biochemestry. 1974; 43: 835-869.
4. Gordon G. Studies on The Intracellular Digestive Process in Mammalian Tissue Culture Cell. Journal of Cell Biology. 1965; 25 (2): 41-55
5. Hirsch I. Lysosomes and Mental Retardation. The Quarterly Review of Biology. 1972; 47 (3): 303-312
6. Phagocytosis And Immunity. The British Medical Journal. 1905; 2 (2338): 1056-1057.