Lysosomes

 Lysosome Function
(the stomach of the cell): The cells waste disposal system that can break down some compounds. It was first historically found  biochemically in rat liver. Also, to me  in everyday life it reminds me of garbage men picking up everyones garbage. It contains acid hydrolase enzymes that break down waste materials and cellular debris. They are membrane-bound vesicles that are made of hydrolytic enzymes. These enzymes degrade proteins, nucleic acids, carbohydrates, and lipids. These are formed in the endoplasmic reticulum. So basically, they have two main functions. To get more in detail of these functions, the explanation of each function is shown below. aysch Lysosomes Retrieved October 17,2012 from Photo Bucket website:http://s300.beta.photobucket.com/user/aysh_photo/media/lysosome.png.html
 
 These functions are:
1: To digest the macromolecules that enter into the cells. These macromolecules are sacs that have about 40 different enzymes that digest substances. The larger molecules of food are broken down smaller. The leftover product diffuses through the lysosomal membrane and are then distributed through the cells. These are served as a building block for some new materials.
2. They break down old organelles that don't function anymore and that outlived themselves so there no longer useful. This happens because cells don't restore themselves which then makes them age. In the cells membrane that is dying, the cell denigrates material which then releases the lysosomal enzymes into the cytoplasm. the digestive organelles then speed up the cells death which is a process called autolysis meaning cell digestion. The products are reused and recycled to make new parts for other cells.
The picture to the left  is what lysosomes look like under a microscope:
Jon P. Boyle and Jay R. Radke (July 2009) A History of Studies that Examine the Interactions of Toxopiusma with its Host cell Emphasis on In Vitro Models Retrieved October 17, 2012 from Science Direct webside: http://www.sciencedirect.com/science/article/pii/S0020751909000939
 
 
 
For a really simple, short way to explain the lysosomes structure and function, look at this youtube
video: maaholadotcom (2011, Feburary 11) Learn Biology: Cells Lysosomes Retrieved from: http://www.youtube.com/watch?v=GhiZml3fQIU&safety_mode=true&persist_safety_mode=1&safe=active

YouTube Video

 

Lysosome Action:

Lysosome-Little Enzyme Packages Retrieved october 16, 2012 from biology 4 kids webside: http://www.biology4kids.com/files/cell_lysosome.html for image

They are described as little digestive machines and go to work when food is eaten or absorbed. There are 3 passways leading to lysosomes. When material is inside, the enzymes are attached and released. they brake down all the complex molecules like complex sugars and
proteins. It's also basically a specialized vesicle that holds a variety of enzymes. They are common in animal cells but are rare in plant cells. Uncontrolled release of the contents of the lysosome into the cytoplasm can cause necrotic cell death. Lysosomes have 50 different enzymes that can hydrolyze proteins, DNA, RNA, lipids, and polysaccharides. Mutations in the genes that encode the enzymes are what cause 30 different human genetic diseases. These are called lysosomal storage diseases because the material accumulates within the lysosomes of affected people.Some human inherited conditions can affect the lysosomes. These defect are called Tay-Sachs disease and Pompe's disease. The people with these disorders are missing one or more of the enzymes(hydrolytic) from lysosomes. Link for image below: http://www.cytochemistry.net/cell-biology/lysosome_sorting.htm


To get a better understanding of how lysosomes are developed and about lysosome storage diseases look at this youtube video:
Willicx (2011, August 21) Lysosomal Starage Diseases, Lysosome Development Retrieved from:http://www.youtube.com/watch?v=-q8voqiXmF8&feature=related&safety_mode=true&persist_safety_mode=1&safe=active
The acid hydrolases enzymes are active at the acidic ph of about 5 is kept within lysosomes but are not at the ph of 7 which is the characteristic of the rest of the cytoplasm. The size of lysosomes vary from around 0.1-1.2 micrometers. At a pH of 4.8, the interior of lysosomes are acidic. The lysosome keeps this pH by pumping protons (H= ions) from the cytosol across the membrane from proton pumps and chloride ion channels. The membrane helps protect the cytosol and and rest of the cell from degradative enzymes in the lysosomes. The cell is also protected from any acid hydrolases that drain into the cytosol. These enzymes are very pH sensitive and don't function very good or they don't function at all in an alkaline environment of the cytosol. This makes sure the molecules of the cytosol and organelles are non lysed just in case there is a leak of the hydrolytic enzymes in the lysosome.

They name lysosome means “realising body” while their enzymes cause lysis meaning disintegration of some materials.
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Where the lysosomes are located in the cell:
    The lysosomes structure as you can see is spherical. They are bounded by a single unit membrane. The reason its own membrane is not digested is because the membrane is very modified so the enzymes are rendered inactive by binding forces. Intracellular conditions regulate and control the release of the enzymes in lysosomes into cellular fluid.
Lysosomes Retrieved October 16, 2012 from think quest webside: http://library.thinkquest.org/06aug/01942/plcells/lysosomes.htm 

 

Primary vs Secondary Lysosomes:

While lysosomes are made the golgi apparatus, theres primary and secondary lysosomes. The primary lysosomes are made on the rough ER while secondary is made on the smooth ER by phagocytosis. This means the process of taking solid materials into the cells. Proteins reach its final stage in making primary lysosomes and a phagosome to make a secondary lysosome. Materials that are important for a cell diffuses into a cell while the waste inside remain trapped. The secondary fuses with the phospholipid bilayer, and waste is release out of the cell. This is a good picture to show my explanation for the process:

 

 Lysosomes and Phayosomes Retrieved October 17, 2012 website: http://biology.kenyon.edu/HHMI/Biol113/lysosomes.htm
 


 
 

 
 
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