Question

Briefly describe pinocytosis and phagocytosis. Differentiate between the two.

Answer 1

Hint: Small particles or substances in the extracellular fluid are ingested into the cell through pinocytosis. This is a mode of taking nutrition in many single celled organisms.

Complete answer:

- Pinocytosis is the ingestion of liquid into a cell by the budding of small vesicles from the cell membrane. For instance, proteins, amino acids, fats, insulin, and lipoproteins, etc.

- Molecules of liquid materials are called pinosomes which are crushed off from the plasma membrane inside the cytoplasm as meager pinocytic vesicles. 

In any case, phagocytosis is not quite the same as that of pinocytosis however the two of them are utilized reciprocally. Phagocytosis is a cellular process for ingesting and eliminating particles larger than 0.5 μm in diameter, including microorganisms, foreign substances, and apoptotic cells, macrophages, neutrophils, monocytes, dendritic cells, etc. 

- It occurs in all protozoans and cells of metazoans, for instance, leucocytes of blood, the reticular cells of the spleen, etc. It is crushed off from the plasma membrane inside the cytoplasm as a food vacuole or phagocytic vesicle. This will furthermore be handled by lysosomes.

Here are some difference between pinocytosis and phagocytosis:

Sl. No	Pinocytosis	Phagocytosis
1.	It is a mass ingestion of liquid materials by a cell.	It is the ingestion of solid material from outside to inside the cell.
2.	Vesicles molded-in pinocytosis are very small in size.	Vesicles outlined in phagocytosis are colossal.
3.	The membrane has receptor pits for getting the materials.	Receptor pits are absent.
4.	Lysosomes assume no function in this process.	Lysosomes are involved in digestion.

Note: Firstly, phagocytosis ingest solid particles which are larger as compared to the particles that the pinocytosis intakes. We also know that the process of pinocytosis is incapable of consuming solid and thus, needs liquid particles that it can dissolve completely.