Structure of the Cell - Non-living Substances Or Cell Inclusion

The inclusion bodies are tiny particles freely suspended and floating within the cytoplasmic matrix. Therefore, they are also referred to as cytoplasmic inclusions. These cell inclusions are formed with decreasing pH and from the pool of soluble fusion proteins within the cell. They are the elementary bodies formed during infectious diseases or within the virus-infected cells, such as rabies, herpes, measles, etc.

• Inclusion bodies are abnormal structures of distinct size and shape, usually observed in nerve, epithelial, or endothelial cells.
• They have a characteristic staining property and are typically composed of proteins.
• Inclusion bodies are nonliving chemical compounds and by-products of cellular metabolism. They are found in both prokaryotes and eukaryotes.
• There are a wide variety of inclusion bodies in different types of cells. In prokaryotic cells, they are mainly formed to store reserve materials.
• In animal cells, they store fats and sugars ready for cellular respiration; in plant cells, they store granules of materials like glycogen, starch, etc.
• Examples of inclusion particles include gas vacuoles, cyanophycean granules, phosphate granules, and glycogen granules.

Granules are tiny particles found in the cytoplasm of both prokaryotic and eukaryotic cells. Granules act as storage units for energy-rich compounds. They store important materials that the cell needs for energy production and other functions. In some cases, granules store waste materials. There are different types of granules:

1. Glycogen Granules: Found in animal and bacterial cells. Store glycogen, a form of sugar used for energy during cellular respiration.
2. Starch Granules: Found in plant cells. Store starch, which is broken down into glucose, to provide energy for the plant.
3. Phosphate Granules: Found in bacteria and other cells. Store phosphate to help the cell make DNA, RNA, and ATP (an energy molecule).
4. Cyanophycean Granules: It is found in blue-green algae (cyanobacteria). Store proteins and nutrients needed for the organism’s growth.

Vacuoles are storage sacs for solid or liquid contents. The central vacuole of some plant cells may occupy 50–90% of the cell volume. Found mainly in eukaryotic cells (both animal and plant cells). Vacuoles are full of cell sap and provide turgidity and rigidity to the plant cell. A vacuole is bound by a single membrane.

• Amino acids, sugars, various organic acids, and some proteins are stored in them.
• They are also present in unicellular organisms. E.g., food vacuoles in amoeba.

1. Vacuoles maintain the osmotic pressure of the cell.
2. They store metabolic byproducts and end products like glycogen, proteins, and water.
3. In animal cells, they store waste products and food.
4. In amoebae, vacuoles store food before digestion.
5. In plant cells, vacuoles are filled with cell sap, which provides turgidity and rigidity.