Lysosome

= = =Lysosomes= = = =What is the "Lysosomes"? and what are the functions???= =Lysosomes are the one of the important organelles in a cell. The lysosomes have sometimes been likened to "The Police Force of the Cell". Even in a place as small as a cell, we need someone to keep things in order. But unlike the police, these lysosomes literally eat things which disturb the natural order of the cell. Lysosomes pick up foreign invaders such as bacteria, food and old organelles and break them into small pieces that can hopefully be used again. If they pick up a really harmful invader, they will eat it up and expel what is left of it out of the cell so that the debris can be removed from the body. =  = = =How can they perform their functions?? = = As you see the picture above, the lysosome is able to do this because it is filled with enzymes. These enzymes are specially made for the lysosome by the rough endoplasmic reticulumand work only at low pH (highly acidic) levels. The reason for this is that the enzymes are so strong that they could eat the whole cell if the lysosome ever let them out. However because they can only work at low pH levels and the rest of the cell has a neutral pH level, they can be neutralized if they accidentally escape from the lysosome. =

=What else does lysosomes do?? = =Lysosomes also play a key role in destroying old organelles within the cell and thus allow them to be replaced with fresher, more effective ones.  This process is known as //autophagy// and is accomplished in two stages. Firstly a membrane is donated by the endoplasmic reticulum. This membrane then surrounds the old organelle. Secondly a lysosome fuses with this membrane to form an //autophagic vacuole//. The lysosome can safely enter it's deadly enzyme contents into this vacuole and destroy the old organelle.  In human liver cells it is calculated that at least one mitochondria undergoes autophagy every 10 minutes. This reflects the highly active nature of the liver as an organ and it's need for a constant supply of fresh organelles.  The electron micrograph below shows a lysosome in the process of destroying a membrane boundmitochondria. = = = = = = = = <span style="FONT-SIZE: 19px; FONT-FAMILY: 'Arial Black', Gadget, sans-serif"> = =<span style="FONT-SIZE: 19px; FONT-FAMILY: 'Arial Black', Gadget, sans-serif"> = =<span style="FONT-SIZE: 19px; FONT-FAMILY: 'Arial Black', Gadget, sans-serif"> = = = = = =<span style="FONT-SIZE: 19px; FONT-FAMILY: 'Arial Black', Gadget, sans-serif"> =