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What Are the Functions of Lysosomes?

The lysosome is an important part of healthy cellular function.
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  • Written By: Solomon Branch
  • Edited By: Allegra J. Lingo
  • Last Modified Date: 24 March 2014
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A lysosome is a specialized part of a cell known as an organelle. The main functions of lysosomes are to get rid of virus and bacteria, digest food particles and other damaged organelles, and help patch cell wall membranes. Lysosomes have special enzymes that allow them to do perform these functions.

The word lysosome stems from the Greek words lysis, meaning destruction or dissolution, and soma, which means body. They were reportedly discovered in 1949 by a Belgian cytologist named Christian de Duve, who also discovered peroxisomes and cell organelles. Lysosomes are sphere shaped, and contain many enzymes that are all classified as acid hydrolases. The functions of lysosomes are a complex topic, but overall they serve as the first line of defense within a cell.

To understand the function of lysosomes, it is easiest to take a more detailed look at the enzymes they produce. There are many enzymes, but the most important ones break down almost all types of substances when put together. The enzyme lipase digests fats, amylase breaks down starch, maltodextrins and amylose, protease and nuclease enzymes breakdown proteins and nucleic acids respectively, and phosphoric acid breaks down monoesters.

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With these enzymes, lysosomes can attack and digest almost anything that comes into, or is already in, a cell wall. There are several ways lysosomes accomplish this, and the most predominant method is phagocytosis, which entails actually ingesting the debris or bacteria. The lysosomes can also have old debris, foreign bacteria, or other dead organelles delivered to them through a process known as autophagy. This particular process can signal the death of the whole cells as well. Lysosomes can also recycle receptor proteins from the cell wall through a process known as endocytosis.

The functions of lysosomes require a pH level of 4.5. This is quite acidic and can cause damage to the cytosol, otherwise known as the intracellular fluid, which is very alkaline. The lysosome has a membrane that surrounds it that prevents damage to the cytosol. It also helps keep the differential balance with the pH of the cytosol by means of a proton pump that pumps out hydrogen molecules. The cytosol is slightly alkaline, approximately 7.2 pH, and this pH difference would otherwise interfere with the functioning of the lysosome’s enzymes.

There are at least 41 diseases than are the result of defects in the lysosomes functions. The most widely known is Tay-Sachs disease. These disease are known collectively as lysosomal storage diseases (LSDs), and they are very rare occurrences.

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Discuss this Article

anon336301
Post 7

@TreeMan and titans62: The cell uses diffusion and osmosis to get rid of waste. -- Sophomore at UW-Madison

jcraig
Post 4

@jmc88 - I tried to look up some information about Tay-Sachs disease, but I couldn't really find anything about the exact mechanisms that cause it. All I could find out was that it is a disease of the nervous system.

As far as the function of the lysosomes, is there any interaction with vacuoles in terms of either transferring materials or pH balance in the cell?

Also, the article mentioned quite a few different molecules you could expect to find in a lysosome that help break down proteins and other molecules. Where are the enzymes created in the first place? Are there other organelles that are responsible for building the enzymes and then passing them on to the lysosome, or does the lysosome create enzymes itself?

jmc88
Post 3

@TreeMan - I may be completely wrong about this, but I seem to remember something in my high school biology class about there being special cells that are designed to seek out old or unnecessary cells and "eat" them. I'm sure during that process, the lysosome materials from one cell and transferred to another.

Since a ruptured lysosome would be dangerous for a cell, I'm curious if there are any diseases or viruses that specifically target the wall of the lysosome and cause it to burst and destroy cells. Maybe that is what Tay-Sachs does. Does anyone know?

TreeMan
Post 2

@titans62 - I am not certain, but my best guess would be that the lysosome connects with the cell membrane and releases the waste materials into the lymph system where the molecules are picked up by white blood cells and carried to other parts of the lymph system to eventually be excreted by the body.

Along those same lines, do white blood cells tend to have more lysosomes compared to something like a nerve cell, for instance?

What happens to the material inside the lysosomes when a cell is destroyed or accidentally ruptures? How does an organism make sure that cells around it aren't damaged?

titans62
Post 1

I had heard of Tay-Sachs disease, but didn't have any idea it was caused by a problem with an organelle in the cell. What exactly happens in Tay-Sachs disease, and how are the lysosomes involved? Is there any way to prevent the disease? If I remember correctly, it is usually something that affects you when you are young.

Something else I was wondering about the lysosome function is how the lysosome actually gets rid of waste materials after it is done breaking them down. Does it just release them into the blood stream somehow, or what happens, since the article mentions the waste materials being very acidic?

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