Difference Between Pinocytosis and Phagocytosis (With Table)

Cells are the smallest unit of life. Both phagocytosis and pinocytosis are essential for a cell to survive. All organisms on this earth follow similar biochemical processes and out of them, endocytosis is the one that has two parts, phagocytosis and pinocytosis. 

Phagocytosis vs Pinocytosis

The difference between Phagocytosis and pinocytosis is that phagocytosis is a process where small particles larger than 0.5 μm are ingested and eliminated by cell. A process where liquid is ingested by cell through small vesicles budded on plasma membrane is called pinocytosis.

Phagocytosis is a cellular process where a cell engulfs foreign particles such as viruses, dust, bacteria etc. with the help of pseudopodia also known as false feet. This is an active process which requires ATP for the activation. The process protects the body from many diseases from viruses, bacteria etc.

Pinocytosis is a cellular process where a cell absorbs nutrients from surrounding fluids.this is also an active process requiring ATP. The nutrients are taken up from the fluids outside the cell. The process plays a significant role in cell growth. The plasma membrane folds itself and absorbs the materials.

Comparison Table Between Phagocytosis and Pinocytosis

Parameters of comparisonPhagocytosisPinocytosis 
Definition 

Cellular process where a cell ingests and eliminates the particles larger than 0.5 μm.Cellular process where a cell ingests liquid particles through small vesicles on plasma membrane.
Process of ingestion

By Pseudopodia(false feet)By invagination or infoldings
Type of particles ingested
Solid
Liquid
Substrate 

Takes up specific substratesTakes up every substrate in contact
Aim

Self defenseTake up nutrients
Vesicles formed

Phagosomes Pinosomes 
Particle nature
Foreign particles, dust, viruses, bacteria etc. 
Sugar, amino acids, hormones, enzymes etc.
Cells who do it

Phagocytosis is performed by macrophages, neutrophils and protozoans.Pinocytosis is performed by secretory cells, blood capillary’s cell linings.

What is Phagocytosis?

Phagocytosis occurs when a cell destroys foreign pathogens such as bacteria, viruses etc. by engulfing them with the help of certain lytic enzymes.. Single-celled organisms such as amoeba also show similar process.

Phagocytic cells, i.e. macrophages and neutrophils in humans protects the body from various kinds of bacteria, viruses and foreign particles. Phagocytosis plays a vital role in human body.

Phagocytosis is an important part of the immune system carried out by phagocytic cells specialized to carry phagocytosis, i. e., neutrophils and macrophages. The immune system prevents the spread of infections and destroys the pathogens with the help of lymphocytes.

Phagocytosis is different from other types of endocytosis because it is very specific and relies on the cell’s ability to bind to the pathogen entered and engulf it. Phagocytosis occurs only when the particle comes in direct physical contact with the cell.

Several cells work for immune system including neutrophils, macrophages, dendritic cells, and B lymphocytes do phagocytosis continuously. The act of engulfing pathogenic particles makes immune system aware of the enemy and prepares it for the next time. Knowing the enemy allows immune system to specifically target similar particles circulating in the body and next time when they enter are killed before they start harming the body.

What is Pinocytosis?

Pinocytosis is the process by which a cell forms a special vesicle called Pinosome and ingests small particles present in extracellular fluid.

The term pinocytosis is derived from two Greek words: ‘pino’ means ‘to drink’ and ‘kytos’ means ‘cell.’ As a result, the term is an abbreviation for “cell drinking.”

 It entails the transport of extracellular fluids along with their content, which are small dissolved molecules. 

As a result, pinocytosis is classified as a type of endocytosis. Pinocytosis needs a significant amount of energy to function and the energy comes in the form of ATP. Therefore, it is a process that includes active transport. Certain ions or amino acids can initiate pinocytosis as the process is not substrate specific.

During this process, the cell drinks surrounding fluids along with the particles present in them. This process can also be called the Engulfing Extracellular Fluid process. Various ions and molecules activate the plasma membrane and start the process where the plasma membrane develops small cavities and absorbs the materials present in the fluids.

Being an active form of transport, it plays an important role in many cellular processes. Excretion of waste material and cleaning of kidneys include some of the important processes in human body.

Main Differences Between Phagocytosis and Pinocytosis

  1. Phagocytosis is the process of ingestion of solid particles through the plasma membrane via lysosomes whereas Pinocytosis is the process of ingestion of small liquid particles through the plasma membrane via pinosomes.
  2. Phagocytosis develops false feet called pseudopodia to engulf particles whereas in pinocytosis, engulfment occurs via invagination or infoldings.
  3. Lysosomes have an important role in phagocytosis but no role in pinocytosis.
  4. Phagocytosis has the protective role, i.e., to protect the body from foreign particles whereas pinocytosis absorbs important nutrients such as amino acids, sugars etc.
  5. Phagocytosis is substrate specific and only allows certain materials to pass through plasma membrane but pinocytosis takes up all the surrounding liquid and is not substrate specific.

Conclusion

Both the processes, i.e. phagocytosis and pinocytosis are biochemical processes which play a very important role in a cell’s life. Cell being the basic unit of life has to undergo many processes in order to survive. Phagocytosis and pinocytosis, both are active processes requiring ATP and different vesicles to absorb and engulf food particles. In both the processes particles are absorbed but the main purpose is different. Phagocytosis where foreign particles are engulfed and pinocytosis where a cell absorbs nutrients. Even after having major differences, these processes are serving the same purpose and that is feeding the cell and in turn the whole body. Both of these are the processes included in endocytosis.

References

  1. https://www.sciencedirect.com/science/article/abs/pii/0304416586900206
  2. https://www.jimmunol.org/content/169/8/4423.short

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