Lysosome is the membrane-bound organelle found in almost all animal cells. These are small fluid-filled sacs containing enzymes which help the cell digest its nutrients and are also responsible for cell destruction after cell death. Lysosomes recycle the organic material of the cell in a process called autophagy. They range in diameter from 50nm to 1um. They contain a single outer membrane made up of phospholipid bilayer which contains enzymes celled
Structure of Lysosome
They range in diameter from 50nm to 1um. They contain a single outer membrane made up of phospholipid bilayer which contains enzymes celled acid hydrolases. These enzymes are capable of breaking down macromolecules. Their outer membrane may be fused with other organelles. There are many enzyme molecules within the single lysosome.
Formation of Lysosome
Lysosomes are specialized vesicles which contain various enzymes. The proteins which make these enzymes are formed in the rough endoplasmic reticulum from where they are transported to Golgi apparatus. The Golgi apparatus then forms enzymes and break off them in the form of small vesicles. These vesicles are lysosomes. The vesicles which are formed in this way are called primary lysosomes and contain enzymes such as proteases and lipases. When primary lysosomes fuse with other vesicles they form secondary lysosomes.
Functions of Lysosome
Lysosomes perform many functions such as autolysis, autophagy, heterophagy, and exocytosis .
Autophagy is the breakdown of material inside the cell by digesting worn-out organelles to reuse the chemicals locked in them.
Heterophagy is the breakdown of materials outside the cell by mechanisms such as phagocytosis (engulfing extracellular solid particles), pinocytosis (engulfing extracellular fluid).
Autolysis is the complete breakdown of the cells which have died.
Exocytosis is the process of destroying harmful materials around the cell.
Lysosomes are highly important organelles of the cell. If they were not present, cells would be vulnerable to various diseases and infections as they remove unwanted materials from the cell and destroy harmful extracellular materials as well.