Difference Between Chemotaxis and Phagocytosis

The key difference between chemotaxis and phagocytosis is that the chemotaxis is a directed migration of cells or an organism along a chemical concentration gradient while phagocytosis is a mechanism that engulfs foreign infectious particles in order to neutralize or destroy them.

Leukocytes are important cells of the immune system. They are white blood cells. Some leukocytes are phagocytes. Phagocytes use phagocytosis to engulf foreign particles. Monocytes, neutrophils, and macrophages are some examples of phagocytes. In order to reach antigens or foreign particles, phagocytes use chemotaxis. Chemotaxis is the movement of cells or organisms towards or away from the chemical stimuli. Furthermore, phagocytes and immune cells mobilize to the site of infection, tissue injury and immune reactions through chemotaxis.

CONTENTS

1. Overview and Key Difference
2. What is Chemotaxis 
3. What is Phagocytosis
4. Relationship Between Chemotaxis and Phagocytosis
5. Side by Side Comparison – Chemotaxis and Phagocytosis in Tabular Form
6. Summary

What is Chemotaxis?

Chemotaxis is the movement of cells or organisms towards or away from the chemical stimuli. It is one of the most important mechanisms used by phagocytes to mobilize into the site of infection or tissue injury. Moreover, chemotaxis is important for many types of cells and organisms. Bacteria find food by chemotaxis. Furthermore, they run away from harmful chemicals due to chemotaxis. In higher organisms, sperms swim towards the egg cells due to chemotaxis.

Chemotaxis can be either positive chemotaxis or negative chemotaxis. If the direction of the movement is towards the chemical stimulus, it is positive chemotaxis. However, if it is away from the chemical stimulus, it is negative chemotaxis. Chemoattractants facilitate positive chemotaxis while chemorepellents facilitate negative chemotaxis.

What is Phagocytosis?

Phagocytosis is a mechanism executed by certain cells or organisms to ingest or engulf foreign particles. The cells that use phagocytosis are known as phagocytes. Several white blood cells are phagocytes. Especially, neutrophils, monocytes, and macrophages act as phagocytes to engulf invaders such as bacteria, viruses, toxins, etc. It is a kind of endocytosis process.

By phagocytosis, solid particles internalize into a structure called phagosome. Once they are trapped inside the phagosome, it fuses with a lysosome and forms a phagolysosome. Then, using the lysosome hydrolase enzymes, the particles inside the phagosome get degraded and destroyed.

What is the Relationship Between Chemotaxis and Phagocytosis?

• Phagocytes migrate into the site of infection and injury by chemotaxis.

What is the Difference Between Chemotaxis and Phagocytosis?

Chemotaxis is the directional movement of cells and certain organisms towards or away from a chemical stimulus. Phagocytosis is a process engulfs foreign particles and destroy them during innate immunity. Therefore, this is the key difference between chemotaxis and phagocytosis. Also, there are two types of chemotaxis as positive chemotaxis and negative chemotaxis. Phagocytosis has no types.

Furthermore, chemotaxis occurs due to a chemical stimulus while phagocytosis does not occur due to a stimulus. So, this is also a difference between chemotaxis and phagocytosis. A further difference between chemotaxis and phagocytosis is that unlike chemotaxis, phagocytosis does not relate to a direction. Also, the involvemennt of lysosomes in the proess contributes to a difference between chemotaxis and phagocytosis. That is; lysosomes are involved in phagocytosis whereas chemotaxis does not involve lysosomes.

The below infographic smmarizes the difference between chemotaxis and phagocytosis.

Summary – Chemotaxis vs Phagocytosis

Chemotaxis is the movement of cells or organisms in response to a chemical stimulus. There are two types of chemotaxis as positive chemotaxis and negative chemotaxis. Chemotaxis is just a locomotion method. Moreover, it works based on a chemical stimulus. On the other hand, phagocytosis is a process used by phagocytes or certain immune cells and certain organisms in order to engulf foreign particles and remove them from the body. It is a kind of endocytosis that internalizes solid particles into a structure called phagosome. Thus, this is the difference between chemotaxis and phagocytosis.

Reference:

1. “Chemotaxis.” NeuroImage, Academic Press, 28 Nov. 2004, Available here.
2. “Phagocytosis.” British Society for Immunology, Available here.

Image Courtesy:

1. “Chtxphenomen1” By Kohidai, L. – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Phagocytosis — amoeba” By Kate Taylor – Kate Taylor (CC0) via Commons Wikimedia