Meaning of Lysosomes

What is Lysosomes:

Lysosomes are characteristic vesicles of animal cells whose function is the transport of proteins sent by the Golgi apparatus and the digestion or breakdown of molecules.

Proteins that are delivered to the lysosomes are tagged by the endoplasmic reticulum with sequences of hydrophobic amino acids called signal peptide.

In biology, lysosomes are organelles that belong to the endomembrane systemdefined as the group of membranes and organelles of eukaryotic cells (which have a cell nucleus) whose main function is the modification, classification and transport of lipids and proteins.

In this sense, the endomembrane system is made up of the endoplasmic reticulum (ER), the Golgi apparatus, lysosomes (animal cell), vacuoles (plant cell) and the plasma membrane.

Structure and function of the lysosome


The structure of a lysosome is quite simple. It is surrounded by a lipid bilayer, a membrane that carries the proteins sent by the Golgi apparatus. Inside it is a mixture of digestive enzymes specific to the cell in which it is found.

In this way, lysosomes have 3 main functions: the transport of proteins, the degradation of molecules by digestive enzymes and the digestion of pathogens or foreign particles that enter the cell from the outside.

Lysosome characteristics

Lysosomes are characterized by being organelles or vesicles of simple structure of animal cells that have hydrolytic or digestive enzymes. These enzymes function as a center for: reuse of old or unused structures, digestion of pathogens, and breakdown of molecules.

The digestion of pathogens is done through phagocytosis. The lysosome fuses with the invaginated pathogen called the phagosome and once together the digestive enzymes destroy the pathogen.

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The chemical composition of lysosomes contains acid hydrolases and a pH of 5.

Lysosomes are part of the animal cell, being the vacuoles that perform the functions of lysosomes in plant cells.

See also: Characteristics of the animal cell.

types of lysosomes

The different lysosomes arise from the type of digestive enzyme they contain and these are determined by the type of cell in which they are found.

More than 40 types of enzymes have been identified in lysosomes depending on the cell in which they are found. The most common is acid phosphatase, which breaks down phosphates in organic molecules.

Other enzymes present in lysosomes and the molecules they degrade are, for example:

  • Proteases: proteins
  • Nucleases: nucleic acids
  • Glucosidases and lysozyme (carbohydrates)
  • Lipases and phospholipases: lipids

In addition, there are 2 other types of lysosomes within cells:

  1. primary lysosome: They are newly formed and do not have any molecules inside in the process of digestion.
  2. secondary lysosome: They are older and already contain the digestion material inside.

Lysosomes and peroxisomes

Peroxisomes differ from lysosomes because they do not belong to the endomembrane system, that is, they do not receive proteins sent by the Golgi apparatus.

Peroxisomes are decomposing organelles, their enzymes contribute to the oxidation process to obtain hydrogen peroxide (HtwoEITHERtwo) and eliminate the toxicity of some substances.

Peroxisomes found in liver cells, for example, are responsible for reducing the toxicity of alcohol in the body.

lysosomes and ribosomes

The relationship between lysosomes and ribosomes starts from protein synthesis in cells. Ribosomes are responsible for this function, also known as translation.

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The translation that ribosomes make of amino acids are used to determine the fate of proteins. Ribosomes specifically translate the amino acid sequence carried by messenger RNA in the cytosol.

Proteins that do not go to the cytosol after translation go to the endoplasmic reticulum, where they will be modified, packaged and transported to the Golgi apparatus.

From the Golgi apparatus, the proteins will be processed again to be sent in vesicles to: the lysosomes, the outside of the cell by secretion, the plasmatic membrane or other parts of the endomembrane system.