Why are Lysosomes known as Suicidal Bag?

All living organisms are composed of cells, the fundamental membrane-bound structure that contains the components of life. It is the basic structural and functional component of all life forms. Large multicellular organisms like humans and other animals are composed of these cells working together with other specialized cells. Every cell has a membrane-enclosed cytoplasm that is filled with a variety of biomolecules, including proteins and nucleic acids. All living things are made up of cells. They might consist of several cells (multicellular) or only one (unicellular). The smallest known cells are mycoplasmas. They provide the body structure and process the food’s nutrients into energy. Cells are of two types, i.e. Eukaryotic cells which contain a nucleus, and prokaryotic cells, in which the nucleus is absent, but a nucleoid region is still present. 

A single-celled organism is known as a prokaryote, in which the nucleus and other membrane-bound cell organelles are absent. Bacteria and archaea are prokaryotes; they are less complex and smaller than eukaryotic cells. A prokaryotic cell has a single circular chromosome that is in touch with the cytoplasm and makes up its DNA. The nuclear area found in the cytoplasm is known as the nucleoid.

In Eukaryotes the nucleus is enclosed within a nuclear envelope. plants, animals, fungi, slime, molds, protozoa, and algae all belong to eukaryotic. These cells are 15 times larger than a typical prokaryote. The presence of membrane-bound organelles in eukaryotes carries out specific activities in a cell. The most important cell organelle is the nucleus, which houses the cell’s DNA. The nucleus gives the eukaryote its name, which means “True Nucleus”. 

Various cell organelles found in eukaryotic cells perform specific tasks in order to carry out life processes. They have been modified to perform one or more essential tasks in a cell. Each organelle in the cell has a unique structure and function. A cell has a variety of organelles. Some are single, while others may come in large numbers. The gelatinous liquid that surrounds the organelles and fills the cell is called the cytosol.

Lysosomes

Lysosomes are small membrane-bound cell organelles in eukaryotic cells or in nucleus-bearing cells. They are located in the cytosol of the cell, moving freely within the cell. They have a simple structure consisting of an outer lysosomal membrane surrounding an acidic interior fluid. They function like small cell stomachs, they digest waste and superfluous cell fragments. 

Cells have specialized vesicles called lysosomes that use hydrolytic enzymes to break down molecules. Vesicles are small fluid spheres that assist in the movement of chemicals inside cells. They are encircled by a lipid bilayer membrane. Only animal cells include lysosomes; a human cell has 300 of them. In addition to breaking down and eliminating cell waste, they are also responsible for digesting complex molecules.

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Lysosome Function

The main function of lysosomes is to eat and destroy undesired cell components, cell waste, and foreign substances that have entered the cell, lysosomes primarily assist in cell metabolism. Large structures and molecules are broken down into simpler parts by the digestive enzymes found in lysosomes, which then return the end products to the cell for processing or disposal. They break down a variety of complex compounds, including lipids, proteins, nucleic acids, and fatty acids. Since lysosomes’ hydrolytic enzymes work best in acidic environments, their pH is kept at or near 5. The lysosomal enzymes are produced in the endoplasmic reticulum and then transferred to the Golgi apparatus. Lysosomes are created within the Golgi apparatus. The lysosomes use the acid hydrolases present in the endoplasmic reticulum to digest the complex proteins and organelles. They act as the cell’s digestive system because it breaks down molecules using enzymes. 

Lysosomes digest various different kinds of molecules. They can digest food molecules that enter the cell into smaller pieces in an endocytic vesicle, this vesicle brings particles into the cell. They perform autophagy, which is the destruction of improperly functioning organelles. In addition, lysosomes also have a role in phagocytosis, which is when a cell engulfs a molecule to break it down, it is also known as “cell eating”. For example, the white blood cells called phagocytes ingest invading bacteria in order to destroy them. and the lysosome encloses the bacteria in a vesicle, later they break down the bacteria.

Why Lysosomes are known as Suicidal Bag?

Lysosomes are cell organelle, they are known as suicide bags of cell because it contains powerful digestive enzymes. Cellular waste and foreign substances are broken down by the hydrolytic enzyme. Lysosomes were first described as “Suicidal Bags of cells” by Christian de Duve. The lysosomes burst and release digestive enzymes during the breakdown of cell structure, which digests the entire cell. They digest the cell in which they are present by their own enzymes, this process is known as autolysis. This leads to the death of cells. Hence, Lysosomes are known as “Suicide bags of cells”.

Structure of Lysosomes

Lysosomes are sphere-shaped membrane-bound organelles with a single outer lysosomal membrane filled with hydrolytic enzymes which have the capability of breaking down the biomolecules. They are generally very small ranging from 0.1-0.5 μm. The membrane is impermeable to the acidic contents of the lysosome. It protects the cell from the digestive enzymes inside the membrane. The lysosome can digest cell waste products, old cell parts, and other debris after the acidic pH is maintained. So that cell fragments, foreign objects, and cell debris are digested while healthy parts of the cell are not attacked, the reductant components are tagged with specific chemicals that identify them as targets. Lysosomes are cell organelles whose function is to break down cellular wastes and debris by engulfing them with hydrolytic enzymes. The lysosome covers the targets and uses some of the hydrolytic enzymes and other chemicals inside the membrane to digest the complex chemical structures and create simple substances the cell can reuse. 

Lysosomes the created from the Golgi apparatus and the enzymes inside it are formed in the endoplasmic reticulum. These enzymes are first transported to the Golgi apparatus in vesicles and then packaged into the lysosomes. Lysosomes also include other enzymes such as proteases, amylases, nucleases, lipases, and acid phosphatases. 

Digestive Enzymes in Lysosomes 

Lysosomes are used in the degradation of proteins and nucleotides enclosed in a membrane. Hydrolytic digestive enzymes are present in lysosomes like proteases, sulfatases, and some glycosidases. These enzymes present in lysosomes are made by the endoplasmic reticulum and transferred to the lysosome. There is a membrane present between these degradative enzymes and the cell matrix to avoid autophagy and cellular autolysis. 

Various digestive enzymes are found in lysosomes, as they can digest proteins, DNA, RNA, and other cell debris. Nearly 50 digestive enzymes are found inside lysosomes. These enzymes are useful in the decomposition of biological polymers like lipids, carbohydrates, and bacteria which prevent the cell from the intrusion of foreign materials. A few digestive enzymes are:

• Glycosidases: Lysosomal alpha-Glucosidase, Hyaluronan Lyase, Galactosyl ceramidase, O-Glycosidase, Chitinase 3, Alpha Galactosidase A, Alpha-L-Fucosidase. 
• Sulfatases: Sulfatase-2, Sulfamidase, Arylsulfatase A, Arylsulfatase B, Arylsulfatase G, Glucosamine-6-Sulfatase, Iduronate 2-Sulfatase, N-Acetylgalactosamine-6-Sulfatase.
• Proteases: Cathepsin V, Cathepsin L, Cathepsin K, Cathepsin H, Cathepsin F, Lysosomal Carboxypeptidase A, Napsin A, Legumain/Asparaginyl Endopeptidase, Galactosylceramidase. 

Function of Digestive Enzymes in Lysosomes

The primary function of lysosomal enzymes is the breakdown of large and complex molecules into simpler ones. These molecules are stored in the cells, known as lysosomal storage cells. Enzymes present in lysosomes are also known as acid hydrolases. A few functions of these enzymes are as follows.

• These enzymes are primarily included in breaking down and engulfing the materials taken up by the cell through endocytosis. 
• These enzymes also participate in phagocytosis and autophagy. 
• As specialized cells, macrophages are the main site for the degradation of large molecules like cell debris, bacteria, or some other biological components to eliminate them outside the cell. 
• These materials get associated with phagosomes in the form of vesicles and get fused with lysosomes to form “phagolysosomes” and digest unwanted materials.  

Importance of Lysosomes

Various internal cell processes lead to the production of waste, and other foreign bodies or substances may intrude into the cell. Such unwanted material should be disposed of from the cell and lysosomes are used for the same. They travel throughout the cell interior and look for material that has been marked as superfluous. The acidic interior of the lysosome can break down biomolecules such as complex carbohydrates, large proteins, and lipids. The resulting simple molecules can either be expelled from the cell or used for repair and maintain the cell structure such as the outer plasma membrane. When Lysosomes expel the products formed from one cell to another cell, it signals the other cell what processes the cell is carrying out and allows other cells to react accordingly.  

FAQs on Why Lysozyme is known as a Suicidal Bag?

Question 1: What are lysosomes?

Answer:

Lysosomes are membrane-bound organelles that include processes such as degrading and recycling cellular waste, cellular signaling, and energy metabolism.

Question 2: Where are lysosomes found? 

Answer:

Lysosomes are found in nearly all eukaryotic cells. Lysosomes are also found in animal cells because they carry enzymes used in the digestion of food and convert it to energy.

Question 3: State some functions of lysosomes. 

Answer:

Lysosomes keep the cells clean by breaking the outside materials like bacteria and worn-out cell organelles into small pieces, they digest the food entering the cell.

Question 4: How do lysosomes work?

Answer:

Lysosomes break down excess or worn-out cell parts. If a cell is damaged beyond repair, lysosomes can help the cell to self-destruct in a process called programmed cell death, or apoptosis. 

Question 5: How are lysosomes formed?

Answer: 

Lysosomes are generally formed by budding of the Golgi apparatus, and the hydrolytic enzymes within them are formed in the endoplasmic reticulum.