Do Animal Cells Have Lysosomes?7 Facts You should Know

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In this post you will find the information about do animal cells have lysosomes, how many lysosomes are there in animal cell and many more detailed facts around it.

Animal cells posses lysosomes in the cytosol of their cytoplasm. They are mainly found in all eukaryotes except plants cell. It functions as digesting the useless and unwanted substances  using hydrolytic enzymes that come inside the cell.

Do animal cells have lysosomes?

All animal cells contain lysosomes with the exception of erythrocytes. Lysosomes are membrane bound structure that are rich in acid hydrolases enzymes. Lysosomes present in animal cell are basically outlined with single membrane forming small vesicular organelle.

Initially lysosomes are rounded but they further changes the morphology according to the substrate found in the cell. Lysosomes are the main component or organelle of the eukaryotic cell. Their main occurrence is found in protistan, protozoans and animal cells with the exception of erythrocytes. Lysosomes are also reported to found in some fungi, seeds, root tips etc.

Are lysosomes only found in animal cells?

Lysosomes are mainly found in protozoans, protistans, animal cell and all eukaryotes may have lysosomes. But in case of plants, they do not posses lysosomes, instead their lysosomal activity is carried out by vacuoles and sphaerosomes.

The main reason for plant cell not having lysosomes is that, it contains cell wall which restricts the entry of unwanted substances inside the cell. However, the presence of lysosomes in the plant cell are not necessary because cell wall act as a main barrier for unwanted substances in plant cell. And if somehow, unwanted substance get into the cell, vacuoles and sphaerosomes perform the function of lysosomes.

Why do animal cells have lysosomes and plants don’t ?

Animal cells are more complex compared to the plant cells. The main reason for animal cell to have lysosomes is that they lack cell wall, so there is no such extra barriers for unwanted substances present inside the cell. Plant cell have large vacuoles, plastids and chloroplast and especially presence of cell wall makes a external barrier for the unwanted substances.

However, the presence of lysosomes in the plant cell are not necessary because cell wall act as a main barrier for unwanted substances in plant cell. And if somehow, unwanted substance get into the cell, vacuoles and sphaerosomes perform the function of lysosomes.

How many lysosomes are found in an animal cell ?

Number of lysosomes can vary depending upon the functions. There are about 50 to 1000 lysosomes are found to be in animal cell. The number depends on the phagocytic activity. Large number of lysosomes are found in leucocytes, histiocytes and macrophages because these are combat cells which act on the unwanted substances that come into contact with our body, so the activity of lysosomes is also very high in them.

Like leucocytes have phagocytic activity, the number of lysosomes is very high in them. The size generally range from 0.2-0.8μm in diameter. Lysosomes are resistant to enzymes because their surrounding membrane protects the lysosomes due to high degree of glycosylation of its protein and lipids. Inside the lysosome, granular fluid is present along with the digestive enzymes. There are fifty hydrolytic enzymes are present inside the lysosomes.

Types of lysosomes

There are two forms of lysosomes, primary and secondary. Primary lysosomes are true lysosomes. They are formed from the maturing face of Golgi body and spreads in the  cytoplasm. Lysosomes contain hydrolases enzymes in the form of minute granules.

Secondary lysosomes are of three kinds, heterophagosomes, autophagosomes and residual bodies. Secondary lysosomes are formed when primary lysosomes are combined with pinosomes and phagosomes. Phagosomes helps in bringing out the food materials from outside to inside the cell. Two or more heterophagosomes are fused together to form big digestive vacuole, these digestive vacuoles digests the big food complex materials with the help of hydrolytic enzymes.

Animal cell lysosomes functions

  • Animal cell lysosomes functions as heterotrophy by ingesting food through phagosomes and digested with the help of lysosomes.
  • Lysosomes also helps in osteogenesis or extracellular digestion that passes out the hydrolases enzyme through ephagy which helps in digestion of cartilage matrix and paves the way for deposition of matrix of bone.
  • During starvation, lysosomes helps in break down of proteins and fat molecules. In more severe conditions, lysosomes also breakdown the cell organelle to get nourishment.
  • Obstruction caused in the body are removed by the group of lysosomes.
  • It also removes useless waste from the body. An example is during parturition, the uterus weighs about 2 kg but after child birth it drops to only 50gm. This is done by the lysosomes which helps in regression of useless materials.
  • Lysosomes performs autophagy, as cell organelles have short life span. The worn out organelle are dumped by lysosomes.
  • The macrophages release lysosomes in the joint area where bony substance get deposited.
  • They are highly present in the leucocytes and macrophages for the digestion of bacteria and other unwanted substances.
  • Lysosomes play crucial role in the initiation of mitosis.
  • Lysosomes dissolves the stored food reserve in seeds for germination.

Difference between Heterophagosomes and autophagosomes

HeterophagosomesAutophagosomes
They are formed when primary lysosomes are fused with phagosomes and pinosomes.They are modified form of secondary lysosomes that performs autophagy or digestion of cellular substance.
Heterophagosomes produces digestive vacuole and brings hydrolysis of complex substance gather by phagosomes and pinosomes.They cover the unwanted substances with smooth membrane to form isolation envelope or isolation body, then lysosomes acts and digests the substance in the vacuole.
The digested substance release from the membrane and become available for the metabolismThe soluble substances formed from the autophagic vacuole is for the metabolism in the cell.

Lysosomes structure in animal cell

Lysosomes in animal cell are generally round and surrounded by single membrane. The size generally range from 0.2-0.8μm in diameter. Lysosomal membrane is usually composed of membrane and lumenal proteins. The pH of lumen region is 4-5. it also contains digestive enzymes.

do animal cells have lysosomes
1.substance enters the membrane through endocytosis 2. Lysosome targets the food vacuole and comes near 3. Lysosome fuse with vacuole and release acid hydrolases.4. hydrolytic enzymes digest the food particles from Wikipedia
  • The enzymes of lysosomes are formed in endoplasmic reticulum and are transported by the Golgi apparatus in the form of small vesicles.  
  • These enzymes are able to break down all the types of biomolecules by hydrolysis. The enzyme requires specific acidic environment.
  • The membrane of lysosomes contains cortisol, cholesterol, heparin, chloroquine, antihistamine. These all components together called membrane stabilizers. It is basic in nature and thus increases the pH and lowers the activity of contained enzymes.

Location of lysosomes in animal cell

Lysosomes are usually found in the cytoplasm of the animal cell. They are secreted by the Golgi apparatus in the form of spherical vesicles that contains acid hydrolases enzymes.

These enzymes are formed in endoplasmic reticulum and trafficked by Golgi body. The membrane of lysosomes contains cortisol, cholesterol, heparin, chloroquine, antihistamine. These all components together called membrane stabilizers.

Difference between autophagy and autolysis

AutophagyAutolysis
It is the digestion of the cell organelle or reserve food material.It is the digestion of the whole cell.
Formation of isolation body takes place. An isolation body is not produced.
Few to several lysosomes are combined with isolation body to form autophagic vacuole.No such vacuole like structures are formed.
Lysosomal membrane does not break.Lysosomal membrane breaks down.
Enzymes remain restricted inside the autophagic vacuole.Enzymes can pass out through membrane into the cytoplasm.
Autophagy comes into play when there is not enough food reserve or starvation of cell.It is resorted for the removal of whole cells and tissues.
Autophagy provides nourishment during starvation.Whole cell is digested, no nourishment is provided.
An example is, autophagy reabsorbs the useless structures during metamorphosis.It occurs in damaged cell and reabsorption of of tadpole tail during metamorphosis.

Which substance make the lysosome membrane fragile?

If there is excess of liposoluble vitamins (K, E, D and  A), hormones, bile salts, ubiquinone, X rays and UV rays make the lysosome membrane weak and fragile. The substances that make the membrane fragile are called membrane labilisers.

What is autolysis of a cell?

It is the self digestion of the whole cell. It occurs when lysosomal enzymes are released outside the cell and enzymes causes the rupturing of their coverings. It occurs in damaged cell and reabsorption of of tadpole tail during metamorphosis.

Conclusion

To wrap up this post we conclude that, animal cells and all eukaryotes contain lysosomes except erythrocytes. It acts as a protective barrier of the cell. Lysosomes perform autophagy and autolysis which is helpful for the body to remove useless by product. They are generally secreted by the Golgi body in the form of small vesicles.

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