Lysosomes structure and function | Complete concept with Tricks | J Biology

Lysosome:

Meaning of Word:
Lyso = Splitting
Some (Soma) = Body

Discovery of Lysosome:
Lysosome was discovered by De Dave in 1949.

Definition of Lysosome:
"They are cytoplasmic organelles and are simple sacs that contain food digesting enzymes known as Hydrolases".

Interesting Facts about Lysosome
:
• They are surrounded by a single membrane.
• They are only present in Eukaryotic cells due to the presence of membranes.
• They are present in both animal and plant cells.

Composition of Lysosome:
Lysosomes are composed of
• Protein
• Lipids
• Enzymes: Contain mainly food digesting enzymes known as Hydrolases which help in the breakdown of food into digestible pieces.

Structure of Lysosome:
They are spherical, single membrane-bounded structures.


Synthesis of Lysosome:
In cells, there is an organelle called the Endoplasmic Reticulum which syntheses protein (enzymes also a protein) with the help of ribosomes. These Proteins (Enzymes) are non-functional and inactive. To convert and modify it into a final product, another organelle is used, known as the Golgi apparatus. Enzymes are processed in the Golgi apparatus and budded off as Golgi vesicles and are called Primary Lysosomes. When food particles enter cells by phagocytosis, the primary Lysosome attaches to the incoming food. Now the Lysosome is called the Secondary Lysosome.
So, before, the function of Lysosome was called Primary Lysosome, while after its combination with food and its functional ability it is now called Secondary Lysosome. After attaching to food particles, the process of digestion is initiated with the help of Hydrolysis enzymes present in the Lysosome. The digested food will be used by cells and undigested food is removed from cells by Exocytosis.



Functions of Lysosome:
i) Help in Intracellular Digestion (As it digests food inside the cell). That's why it is also known as the Stomach of the cell.
ii) Lysosomes help in autophagy (self-eating), so some old and damaged parts of cells are also digested, and cells may be recycled and renewed.
iii) Sometimes the Lysosome engulfs all old cells with the help of enzymes. That's why it is also known as the Suicidal Bag.
iv) Also help in the developmental process, e.g. engulfing of a tadpole in a frog.

Other Names of Lysosomes
• Splitting Body
• Stomach of the cell
• Suicidal Bag

Why is Lysosome known as the Suicidal Bag?
Because Lysosomes perform the process of autophagy (self-eating) and also eat old cells. The enzymes inside the Lysosome perform their function in an acidic environment. Sometimes the membrane of the Lysosome bursts and the acidic environment releases into cytoplasm which damages the whole cell, that’s why it is known as the Suicidal Bag.

Why is Lysosome known as the Stomach of Cell?
Because it helps in intracellular digestion, i.e. digesting food inside the cell to make it diffusible, it is called the Stomach of the Cell.

Malfunctions of Lysosome;
As Lysosome performs the work of Digestion. If one or more enzymes are disturbed due to some reason like mutation etc., the food component will remain undigested in cells and can cause Storage Diseases such as;
1. Glycogenosis type II: In this disease an enzyme that converts glycogen to glucose is absent, hence glycogen remains undigested and liver and muscle cells are filled with glycogen.
2. Tay Sach's disease: In this disease an enzyme that converts fatty substances is absent. By which fatty substances are accumulated in brain cells which lead to mental problems and even death.


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J Biology - Instructor Jawad Ahmad