Does Lysosome Have Membrane? 5 Complete Facts

Lysosome is a eukaryotic organelle that helps the cell to break down unwanted substances and various cellular debris and dead cells. Let us see if lysosome has membrane.

Lysosomes possess a single membrane that is found mostly in eukaryotes. The thickness of the membrane is always less than 100mm in diameter.

Let us discuss why lysosome have a single membrane, what is it called, why lysosome do not digest their membrane and many other related questions in this article.

Why do lysosomes have a single membrane?

Lysosome is the most common example of a membrane-bound organelle. Let us check why lysosome have a single membrane.

Lysosomes have a single membrane because they can maintain a suitable acidic pH due to the presence of enzymes also known as hydrolytic enzymes. Such enzymes are maintained within a lysosomal single membrane.

With the presence of a single membrane, lysosome can easily do the activity of endocytosis in which it can engulf the material from outside and digest them inside of an organelle.

Image from Wikipedia
Electron micrograph of endosomes in human HeLa cells. Early endosomes (E – labeled for EGFR, 5 minutes after internalisation, and transferrin), late endosomes/MVBs (M) and lysosomes (L) are visible. Bar, 500 nm.

Structure of lysosome membrane

The packaging material of the Golgi body is the main source for the formation of lysosomal structures. Let us look at the structure of lysosome in detail below.

There are different structural details and functions of lysosomes which are listed as below:

  • The following is the order through which its origin takes place: Outer nuclear membrane -> Endoplasmic reticulum -> Golgi body -> Lysosomes.
  • The outer membrane of the nucleus is mainly attached to rough ER rather than a smooth ER. The membrane of ER is responsible to form some vesicles and tubules to form the Golgi body.
  • The vesicles from the Golgi body form an endosome and later convert into one tiny vesicle-like structure which has enveloped and made up of a single layer of a phospholipid bilayer that is filled with some digestive hydrolytic enzymes known as lysosomes.
  • It can do the activity of exocytosis as well as digest the material via autophagy (within a cell) and heterophagy (outside the cell)
Source: Wikipedia
From left to right: Phagocytosis, Pinocytosis, Receptor-mediated endocytosis.

What is the lysosome membrane called?

Lysosomes are a part of vesicles as well as a bud from the single plasma membrane. Let us see the name of lysosomal membrane.

The lysosomal membrane is made up of a phospholipid bilayer that is generally known as the membrane lumen. The lumen is one kind of volume that is enclosed within the lysosomal membrane.

Why do lysosomes not digest their membranes?

Lysosomes contain hydrolase which cleaved various microbes and other cellular debris. Let us explore why lysosomes do not digest their membranes.

The factors that prevent lysosomes from digesting their membrane are listed below:

  1. Due to the thickness of the membrane.
  2. Due to high lipid content in the membrane.
  3. Proteins of the lysosomal membrane are highly glycosylated making them resistant to proteases.
  4. There is a thick glycocalyx (protective carbohydrate and sialic acid residues) inside the lysosomal membrane.
  5. Hydrolases inside lysosomes are only active at certain pH only
  6. In the latest study, it is seen that the inner layer of lysosomes which is phospholipid only has a family of proteins that will allow some antihydrolases to come in.
  7. Lysosomal membranes remain intact until undergoing apoptotic cell destruction. Lysosomal enzymes become active only when pH is 4.8 or below.

Does lysosome have a double membrane?

Lysosome provides room for some process such as phagocytosis as well as autophagocytosis for the removal of unwanted cellular parts. Let us learn if they possess double membrane.

Lysosomes do not have a double membrane. It has a single membrane that can fuse with membrane vesicles to form endosomes via endocytosis in which the molecule is taken up inside from the outside of the lysosome.

Phagocytosis from Wikiwand.com

Conclusion

From the article, it can be concluded that lysosomes have a single membrane that plays a very important role in different kinds of cellular events such as autophagy, heterophagy, phagocytosis, and many more.

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