What is the Difference Between Cell Organelles and Cell Inclusions

The main difference between cell organelles and cell inclusions is that the cell organelles are membrane-bound compartments that perform a particular function in the cell whereas the cell inclusions are non-living materials in the cytoplasm. 

Cell organelles and cell inclusions are two types of components in the cell with different functions. Furthermore, nucleus, mitochondria, chloroplasts, Golgi apparatus, endoplasmic reticulum, lysosomes, centrioles, and, microtubules are some cell organelles while cell inclusions include pigments, granules of glycogen and lipids, and various secretory products. 

Key Areas Covered 

1. What are Cell Organelles
     – Definition, Types, Function
2. What are Cell Inclusions
     – Definition, Types, Function
3. What are the Similarities Between Cell Organelles and Cell Inclusions
     – Outline of Common Features
4. What is the Difference Between Cell Organelles and Cell Inclusions
      – Comparison of Key Differences

Key Terms 

Biochemical Reactions, By-Products, Cell Inclusions, Cell Organelles, Cytoplasm, Membrane-Bound Structures 

What are Cell Organelles 

Cell organelles are the membrane-bound compartments in the eukaryotic cells that are specialized to perform a unique function. This means a unique biochemical reaction occurs inside every organelle. Since it is enclosed by a membrane that resembles the plasma membrane, a unique biochemical environment can be maintained inside the organelle, which facilitates the occurrence of that particular biochemical reaction. The main types of cell organelles and their functions are as below. 

Figure 1: Cell Organelles

• Nucleus – contains genetic material of the organism and undergoes DNA replication and transcription
• Plasma membrane – encloses the contents of the cell, providing the shape. It allows the transport of molecules in and out of the cell.  
• Cell wall – only occurs in plant cells. It gives the shape and turgidity to the plant cells. 
• Cytoskeleton – contains microtubules, microfilaments, and intermediate filaments. It maintains cell shape, keeps the other organelles in place, and is responsible for the cell movement.  
• Ribosome – facilitates the translation. Eukaryotes contain large ribosomes, which are 80S. 
• Mitochondria – undergo cellular respiration. It is the power-house of the cell. 
• Chloroplasts – a type of plastids in plants and undergoes photosynthesis. 
• Endoplasmic reticulum – is a network of membranes involved in the transport of materials. 
• Golgi apparatus – consists of sacs like Cisternae and is responsible for the modification, packaging, and transport of molecules. It forms lysosomes. 
• Vacuole – occurs in plant cells. It stores cell sap and provides turgidity to the cell. 
• Lysosomes – contains digestive enzymes for the intracellular digestion of food. 
• Peroxisomes – contains oxidative enzymes for the lipid destruction. 

What are Cell Inclusions 

Cell inclusions are intracellular, non-living substances that do not carry out any type of biochemical reaction. Moreover, they are not enclosed by the plasma membrane. Thus, the main function of inclusions is to store secretary products, nutrients, and pigment granules in the cytoplasm. Some examples of cell inclusions are glycogen granules in the muscle and liver cells, lipid droplets in fat cells, pigment granules in the skin and hair cells, vacuoles with crystals, and water-containing vacuoles. 

Figure 2: Granulocytes with Granules of Digestive Enzymes

• Glycogen granules – store glycogen and are located near the smooth endoplasmic reticulum. Glycogen is the main storage form of glucose in the cell. 
• Lipid granules – mainly occur in adipocytes and hepatocytes. They store lipids in the form of triglycerides. 
• Pigments – most common type of pigments in the body apart from hemoglobin is melanin, which is produced by the skin and hair cells, pigment cells in the retina, and the nerve cells in the substantia nigra. 
• Crystals –  crystals of proteins produced by various organelles in the cell are stored in the cytoplasm in the form of granules. 
• Secretory products – granules store various types of secretory products including neurotransmitters, hormones, digestive enzymes, fibrous proteins, mucus, HCl, etc. for future use. 

Similarities Between Cell Organelles and Cell Inclusions 

• Cell organelles and cell inclusions are two types of cellular components with a unique function. 
• Both of them are embedded in the cytoplasm. 

Difference Between Cell Organelles and Cell Inclusions 

Definition 

Cell organelles refer to membrane-bound compartments or structures in a cell that performs a special function while cell inclusions refer to nonliving material in the protoplasm of a cell, such as pigment granules, fat droplets, or nutritive substances.  This is the main difference between cell organelles and cell inclusions.

Occurrence 

Also, cell organelles exclusively occur in eukaryotes while cell inclusions occur in both eukaryotic and prokaryotic cells. 

Living/Non-Living 

Cell organelles are living components while cell inclusions are non-living. This is an important difference between cell organelles and cell inclusions.

Membrane-Bound or Not 

Another difference between cell organelles and cell inclusions is that the cell organelles are membrane-bound structures while cell inclusions are not enclosed by membranes. 

Correspondence 

Cell organelles perform a unique function inside the cell while cell inclusions are formed as a result of the functioning of the cell organelles. Hence, cell inclusions mainly serve as storage compartments. 

Biochemical Reactions 

The biochemical reaction process also attributes to a difference between cell organelles and cell inclusions. That is; the unique biochemical reactions occur inside the cell organelles while cell inclusions contain the end products of those biochemical reactions. 

Self-Replication 

Self-replication is another difference between cell organelles and cell inclusions. Cell organelles are self-replicative while cell inclusions are not self-replicative. 

Examples 

Cell organelles include the nucleus, mitochondria, chloroplasts, Golgi apparatus, endoplasmic reticulum, lysosomes, centrioles, microtubules, filaments, etc. are cell organelles while cell inclusions include pigments, granules of glycogen and lipids, and various secretory products. 

Conclusion 

Cell organelles are membrane-bound structures that undergo unique biochemical reactions inside the cell. Some cell organelles include nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, etc. On the other hand, cell inclusions store the by-products of the cell organelles and nutrients including glycogen, lipids, and, secretory products. Therefore, the main difference between cell organelles and cell inclusions is their structure and function. 

Reference:

1. “Cellular Organelles and Structure.” Khan Academy, Khan Academy, Available Here
2. Trisha. “Notes on Cell Inclusions (With Diagram).” Biology Discussion, 27 Aug. 2015, Available Here

Image Courtesy:

 1. “Cell-organelles-labeled” By Koswac – (CC BY-SA 4.0) via Commons Wikimedia  
2. “1907 Granular Leukocytes” By OpenStax College – Anatomy & Physiology, Connexions Web site, Jun 19, 2013. (CC BY 3.0) via Commons Wikimedia  

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