Concept Paper Example: Phagocytosis
The word Phagocytosis comes from Greek origin and can be broken down into three parts, “phago” means devouring, “cyte” means cell, and “osis” means condition (Patton.) What exactly is Phagocytosis, what does it do, and how does it work with other forms of transport to help living organisms thrive? To simply explain, phagocytosis is a type of active transport where large particles are allowed into a cell through the semi-permeable plasma membrane of a cell and enter the cell through vesicles.
Figure 1: shows the phagocytosis process broken up into four steps.
The Editors of Encyclopaedia Britannica. “Phagocytosis.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 27 May 2020, https://www.britannica.com/science/phagocytosis.
These Vesicles bind together with the Lysosomes to consume the particles and the remaining waste is removed. The Immune systems within the majority of cells use phagocytosis to destroy particles the cell sees as destructive. According to Bilologydictionary.net, An example within the human body of phagocytosis would be white blood cells because their main role in the body is to find and eradicate all invading bacteria. Some single-celled organisms such as protists even use this form of active transport to eat their food.
The main function of phagocytosis is to digest particles that are allowed into the cell. This form of active transport is one of two types of endocytosis, (the other being pinocytosis.)
Phagocytosis is different from pinocytosis because pinocytosis is the consumption of smaller liquid droplets, whereas phagocytosis is the consumption of larger, solid particles.
Figure 2: gives a visualization of the difference between the two forms of endocytosis.
Gonz, Amanda. “Phagocytosis and Pinocytosis Diagram - Quizlet.” Quizlet, Quizlet Inc., 2018, https://quizlet.com/261232487/phagocytosis-and-pinocytosis-diagram/.
Another difference between the two forms of endocytosis is that in pinocytosis the particles ingested do not need to be broken down or digested by a lysosome because they are already so small, so instead, the vesicle off-loads its cargo directly into the cell.
To begin the process of phagocytosis, the organism performing the process will be in a state of activation. This occurs only when the cell(s) of the organism are near parts of bacterial or whole bacteria cells parts. Receptors on the external parts of the cells attach to these bacteria particles which cause the activated cells to respond. Within the immune system, cells pick up chemical signals and send cells to migrate toward the invading bacteria. This process is called Chemotaxis. These cells then adhere to the particle that it is intending to consume. Next, the bacteria are ingested by the cells and the molecules are enclosed in a phagosome or vesicle and transported deeper into the cell. A lysosome fuses with the phagosome and the particle is dissolved. The lysosome then uses a series of hydrolytic enzymes to break down the bacteria’s molecules.
Figure 3: Demonstrates how phagocytosis and exocytosis work together within a cell.
Lindell, Kristoffer. “Principles of Phagocytosis.” Research Gate, Researchgate, https://www.researchgate.net/figure/Principles-of-phagocytosis-The-bacteria-are-recognized-by-surface-receptors-on-a_fig2_267861146.
Any waste that the cell cannot use is released from the body through a process opposite to endocytosis called exocytosis.
Work Cited:
Patton, Kevin T., and Gary A. Thibodeau. “Chapter 6: Cell Function.” Anatomy & Physiology, Tenth ed., Elsevier/Mosby, 2019, pp. 98–119.
Biologydictionary.net Editors. "Phagocytosis." Biology Dictionary, Biologydictionary.net, 05 Apr. 2017, https://biologydictionary.net/phagocytosis/.
