Lysosomes+and+Peroxisomes


 * //__L y s o s o m e s __//**

//**Structure:** A membrane-bound vesicle of digestive enzymes found in eukaryotic cells
 * Function:** Digest particles and structures in the cell//



The word lysosome is derived from the Greek word //lysis,// which means dissolution or destruction and //soma,// which means body. Reasonably, lysosomes are single membrane-bound organelles containing hydrolytic enzymes that digest macromolecules. Their cellular construction begins at the rough endoplasmic reticulum where hydrolytic enzymes and lysosomal membranes are made and then transported to the golgi apparatus by a transport vesicle. Lysosomes then bud from the golgi apparatus and remain in the cell's cytosol, a semifluid medium in the cytoplasm region. When particles such as viruses enter the cell membrane by phagocytosis, a process where cells eat by engulfing substances, the lysosome fuses with the vesticle containing the foreign substance and releases its digestive enzymes.



Lysosomes also play a role in 'keeping the cell refreshed' in a sense. They digest used or worn out organelles such as the mitochondria, by fusing with the structure and delivering their hydrolytic enzymes. This process allows the cell to recycle its own organic material, also known as autophagy. Lysosomes are further the culprits of 'cell death' in which the cell digests itself when it can no longer function at its optimal rate. This is known as autolysis.

 __Lysosomes in Biological Development__ The role of a lysosome in digesting and recycling an organism's organic material is vital to their development. Take for instance, the growth of a tadpole into a frog--lysosomes destroy the cells of the tail and aid in the metamorphosis of a swimming creature into an amphibian. Human embryotic hands are also webbed before lysosomes digest the tissue between the fingers.

__Clinical Revelance__

Lysosomal storage diseases are inherited disorders that affect lysosomal metabolism. A person inflicted with such an illness lacks an active hydrolytic enzyme necessary in a lysosome's digestive fluid. The result is a homeostatic imbalance. Examples of lysosomal storage diseases include Pompe's disease, where the liver is damaged by an accumulation of glycogen due to the absence of lysosomal enzymes. Tay-Sachs disease is another lysosomal storage infliction where the brain becomes impaired by a deluge of lipids in the cell. Again, the cause of the accumulation in lipids is due to the lack of a lysosomal enzyme.

media type="custom" key="2371035" [|Lysosomal Video]
 * Media Gallery**

media type="youtube" key="dh01ivlV_D0" height="344" width="425"

[|Animated lysosome video] (highly recommended) [|Slideshow video on lysosomes] [|Interactive game]
 * External Links**

1. "Cell Structure: Lysosomes." __Biology4Kids__. 27 Oct 2008 . 2. Campbell, Reece, Mitchell, Neil A., Jane B., Lawrence G. __Biology__. 5th. Menlo Park, CA: Benjamin/Cummings, 1999. 3. "Lysosomes." __Cellupedia__. 27 Oct 2008 . 4. Davidson, Michael. "Lysosomes." __Molecular Expressions__. 09 May 2005. Molecular Expressions. 28 Oct 2008 < [|http://www.molecularexpressions.com/cells/lysosomes/images/lysosomesfigure1.jpg] >. 5. "Pompe's Disease." __MDA__. 2006. Helping Jerry's Kids. 28 Oct 2008 . 6.    "Plant Cell." __Think Quest__. 2006. 28 Oct 2008 < http://library.thinkquest.org/06aug/01942/plcells/thinkquest/lysosomes.jpg <span style="FONT-FAMILY: Arial, Helvetica, sans-serif">>. <span style="FONT-FAMILY: Arial, Helvetica, sans-serif"><span style="FONT-FAMILY: Arial, Helvetica, sans-serif">7. Farabee, M.J.. "Cellular Organization." __Cells II__. 28 Oct 2008 < <span style="FONT-FAMILY: Arial, Helvetica, sans-serif">http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookCELL2.html <span style="FONT-FAMILY: Arial, Helvetica, sans-serif">>. <span style="FONT-FAMILY: Arial, Helvetica, sans-serif"> <span style="FONT-FAMILY: Arial, Helvetica, sans-serif">8. "Molecular Cell Biology." __Nature Reviews__. Nature Reviews. 28 Oct 2008 < <span style="FONT-FAMILY: Arial, Helvetica, sans-serif">http://www.nature.com/nrm/journal/v3/n2/fig_tab/nrm732_F2.html <span style="FONT-FAMILY: Arial, Helvetica, sans-serif">>. <span style="FONT-FAMILY: Arial, Helvetica, sans-serif">9."Lysosomes and Peroxisomes." 28 Oct 2008 < <span style="FONT-FAMILY: Arial, Helvetica, sans-serif">http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/L/Lysosomes.html <span style="FONT-FAMILY: Arial, Helvetica, sans-serif">>.
 * Works Cited**

//**__ P e r o x i s o m e s __

Structure:**// //A single membrane, cytoplasmic organelle that is spherical in shape and contain digestive enzymes// //**Function:** Uses digestive enzymes to break down toxic material in the cell.//

<span style="FONT-FAMILY: 'Arial','sans-serif'">Peroxisomes are cytoplasmic organelles that contain oxidative enzymes that break down toxic chemicals in the cell. <span style="FONT-SIZE: 9.5pt; FONT-FAMILY: 'Arial','sans-serif'; mso-bidi-font-size: 9.0pt"> It got its name from using the enzymes to transfer hydrogen from various substrates to oxygen and produces hydrogen peroxide as a byproduct. These organelles may have many different functions. Some of them use oxygen to break down the fatty acids into smaller molecules which then can be transported to mitochondria as fuel for cellular respiration. Peroxisomes can also oxidize alcohol which is an important reaction in liver and kidney cells. The hydrogen peroxide formed by peroxisome is toxic but the organelle contains an enyzme that converts the hydrogen peroxisde to water. They also play a role in bile acid synthesis, cholesterol synthesis, plasmalogen synthesis, amino acid metabolism, and purine metabolism. There are specialized peroxisomes called glyoxysomes that are found in the fat-storing tissues of plant seeds. They contain enyzmes that initiate the conversion of fatty acids to sugar. <span style="FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman','serif'; mso-fareast-font-family: 'MS Mincho'; mso-ansi-language: EN-US; mso-fareast-language: JA; mso-bidi-language: AR-SA; mso-bidi-font-size: 11.0pt; mso-fareast-theme-font: minor-fareast; mso-bidi-theme-font: minor-bidi"><span style="FONT-FAMILY: 'Times New Roman', Times, serif"><span style="FONT-FAMILY: Arial, Helvetica, sans-serif"> Unlike lysosomes, peroxisomes do not come off of the endomembrane system. They grow by taking in protein and lipids made in the cytosol and when they reach a certain size, they'll split into two.

[|Cellular Division]

<span style="FONT-FAMILY: Arial, Helvetica, sans-serif"><span style="FONT-FAMILY: Arial, Helvetica, sans-serif"> <span style="FONT-FAMILY: Arial, Helvetica, sans-serif"><span style="DISPLAY: block; FONT-SIZE: 90%; FONT-FAMILY: Arial, Helvetica, sans-serif; TEXT-ALIGN: left">__ Peroxisomal Disorders __ <span style="FONT-SIZE: 11pt; FONT-FAMILY: 'Arial','sans-serif'; mso-bidi-font-size: 12.0pt"> <span style="FONT-SIZE: 10pt; FONT-FAMILY: 'Arial','sans-serif'; mso-bidi-font-size: 12.0pt">Peroxisomal disorders result from a reduced number or complete absence of peroxisomes and would affect the functions of many enzymes. Some disorders include Zellweger syndrome, neonatal adrenoleukodystrophy, hyperpipecolic acidemia, and infantile Refsum disease. Also, some people may have decreased muscle tone, cerebral malformations, seizures, and eye abnormalities. No specific treatment exists for peroxisomal disorders at this moment and unfortunately, nearly all of the disorders are lethal.

[|Neonatal adrenoleukodystrophy]

To know more about Peroxisomes and other organelles, visit a fun [|interactive animation]!

1. Campbell, Neil A. __Biology__. 5th ed. Menlo Park, CA: Addison Wesley Longman, 1999. 1-1175. 2. "Eucaryotic Cell Interactive Animation." __CELLS alive!__ 2006. 24 Sept. 2008 <http://www.cellsalive.com/cells/cell_model.htm>. 3. "Peroxisomes - Another Enzyme Package." __Biology4Kids.com__. 1997. 24 Sept. 2008 <http://www.biology4kids.com/files/cell_peroxisome.html>. 4. "Cell." __Encyclopædia Britannica__. Encyclopædia Britannica Online. 27 Oct. 2008 <http://www.britannica.com/ebchecked/topic/101396/cell>. 5. "Metabolic disease." __Encyclopædia Britannica__. Encyclopædia Britannica Online. 27 Oct. 2008 <http://www.britannica.com/ebchecked/topic/377311/metabolic-disease>. 6. "Peroxisome." __World Book__. 2008. 27 Oct. 2008 http://www.worldbookonline.com/student/dictionary?lu=peroxisome.
 * Works Cited**