Differentiate between Phagocytosis and Pinocytosis

Phagocytosis and pinocytosis are both forms of endocytosis, where cells take in substances from the outside environment. 

Although both processes are similar, they differ on the basis of several factors:

1. On the basis of Type of Material Engulfed:

In phagocytosis, the cell engulfs large solid particles like microorganisms, cell debris, or dust particles. For example, a macrophage engulfing a bacterium during an immune response.

In pinocytosis, the cell engulfs extracellular fluid along with dissolved small molecules and nutrients. For example, cells in the intestine absorb dissolved nutrients through pinocytosis.

2. On the basis of Nature of the Process:

Phagocytosis is often considered as "cell eating" because it involves the intake of solid matter into the cell.

Pinocytosis is termed as "cell drinking" because it involves the intake of fluids along with dissolved substances.

3. On the basis of Vesicle Size Formed:

During phagocytosis, large vesicles called phagosomes are formed that can be clearly seen under a microscope.

In pinocytosis, the vesicles formed are much smaller, and they are usually too tiny to be easily distinguished under a microscope.

4. On the basis of Specificity:

Phagocytosis is usually a selective process. Cells recognize specific particles, such as bacteria, through surface receptors before engulfing them.

Pinocytosis is generally non-specific. The cell engulfs whatever fluid and solutes are present in the extracellular environment without any specific selection.

5. On the basis of Requirement of Surface Receptors:

In phagocytosis, the binding of the particle to specific receptors on the cell surface is essential for the process to begin.

In pinocytosis, surface receptors are not necessarily required, the membrane simply folds inward randomly to engulf extracellular fluid.

6. On the basis of Energy Consumption:

Phagocytosis requires more energy as it involves the engulfment of large particles and the active extension of pseudopodia.

Pinocytosis requires relatively less energy because it involves the passive engulfment of fluid by invagination of the membrane.

7. On the basis of Occurrence:

Phagocytosis is mainly performed by specialized cells like macrophages, neutrophils and amoebas.

Pinocytosis can occur in almost all types of cells where nutrient absorption from extracellular fluid is needed.

8. On the basis of Final Fate of Vesicle:

In phagocytosis, the phagosome usually fuses with a lysosome, where the solid particle is digested by enzymes.

In pinocytosis, the small vesicles may fuse with endosomes or lysosomes where the fluid contents are processed or absorbed.









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