The human body comprises about 50 to 75 trillion cells. The cell is the smallest unit of life and is often called the building block of life. A single cell is made up of many different organelles, that have specific functions, such as the nucleus, Golgi bodies, mitochondria, peroxisomes and lysosomes.

LysosomesLysosomes are membrane bound organelles that are found in the cytoplasm of both plant and animal cells. The word lysosome was derived from two Greek words, 'lysis' which means destruction or dissolution and 'soma' which means 'body'. Lysosomes were discovered in 1949, by a Belgian cytologist, Christian de Duve.

StructureLysosomes are actually membranous sacs filled with enzymes. They are found in all eukaryotic cells and act as 'garbage disposal' or the 'digester' of the cell. Lysosomes are spherical bag like structures that are bound by a single layer membrane, however, the lysosome shape and size may vary to some extent in different organisms. The lysosome size ranges between 0.1 to 1.2μm. The membrane that surrounds the lysosome, protects the rest of the cell from the hydrolytic or digestive enzymes that are contained in the lysosomes.

Lysosomes are manufactured by the Golgi apparatus, by budding, in the cell and the various digestive enzymes, that are present in the lysosomes are produced in the endoplasmic reticulum. These enzymes are then transported to the Golgi apparatus and are distributed to the lysosomes. Some examples of enzymes present in the lysosomes include nucleases, proteases, lipases and carbohydrases. These enzymes are used to dissolve nucleic acids, proteins, lipids and carbohydrates, respectively. All these enzymes are typically hydrolytic and can digest cellular macromolecules. Lysosomes are acidic, with a pH of 4.8. This acidic pH is maintained by pumping protons, from the cytosol that has a pH of 7.2. The protons are pumped across the membrane via proton pumps and chloride ion channels. The membrane thus acts as a protective barrier, that protects the cytosol and the rest of the cell from the hydrolytic enzymes within the lysosome.

FunctionLysosomes act as disposal system of the cell. They break down complex proteins,

carbohydrates, lipids and other macromolecules into simpler compounds. These simple compounds are returned to the cytoplasm and are used as new cell building materials. They are used for digestion of cellular waste products, dead cells or extracellular material such as foreign invading microbes, that pose a threat to the cell by phagocytosis process. However, phagocytosis is just one process that helps to get rid of unwanted material in the cell. Lysosomes are also involved in other digestive processes including endocytosis and autophagy. Another interesting function of the lysosomes is to repair the damage to the plasma membrane. They serve as membrane patch and help in sealing the wound in the plasma membrane. Lysosomes are also involved in programmed cell death, or autolysis, which is a catabolic process involving degradation of the cell's own components. This is the reason why lysosomes are often known as 'suicide sacs'.

DefectsAny malfunctioning of the lysosomes or any of the digestive proteins, results in lysosomal storage diseases, such as Tay-Sachs disease and Pompe's disease. These diseases are caused by defective function of the lysosomes or in absence of any of the digestive proteins or lysosomal hydrolytic enzymes.

This was all about the structure of lysosome and its functions. So, now you know how important these microscopic organelles are!By Amruta DeshpandeRead more at Buzzle: http://www.buzzle.com/articles/lysosome-structure.html

Lysosomes - Little Enzyme PackagesYou will find organelles called lysosomes in nearly every animal-like eukaryotic cell. Lysosomes hold enzymes that were created by the cell. The purpose of the lysosome is to digestthings. They might be used to digest food or break down the cell when it dies. What creates a lysosome? You'll have to visit theGolgi complex for that answer. 

A lysosome is basically a specialized vesicle that holds a variety of enzymes. The enzyme proteins are first created in the rough endoplasmic reticulum. Those proteins are packaged in a vesicle and sent to the Golgi apparatus. The Golgi then does its final work to create the digestive enzymes and pinches off a small, very specific vesicle.

That vesicle is a lysosome. From there the lysosomes float in the cytoplasm until they are needed. Lysosomes are single-membrane organelles. 

Lysosome ActionSince lysosomes are little digestion machines, they go to work when the cell absorbs or eats some food. Once the material is inside the cell, the lysosomes attach and release their enzymes. The enzymes

break down complex molecules that can include complex sugars and proteins. But what if food is scarce and the cell is starving? The lysosomes go to work even if there is no food for the cell. When the signal is sent out, lysosomes will actually digest the cell organelles for nutrients. 

Why Don't They Digest the Cell?Here's something scientists are still trying to figure out. If the lysosome holds many types of enzymes, how can the lysosome survive? Lysosomes are designed to break down complex molecules and pieces of the cell. Why don't the enzymes break down the membrane that surrounds the lysosome?