Difference Between Plasmolysis and Deplasmolysis

Main Difference – Plasmolysis vs Deplasmolysis

Water molecules move across the cell membrane by osmosis. The movement of water molecules into the cells is known as endosmosis. The opposite of the endosmosis is exosmosis. Water molecules move out of the cells in exosmosis. Plasmolysis and deplasmolysis are two processes that occur in the cells during the two types of osmosis. The main difference between plasmolysis and deplasmolysis is that plasmolysis is the constriction of the protoplast as a result of the water loss caused by exosmosis whereas deplasmolysis is the swelling up of the protoplast as a result of gaining water by endosmosis.

Key Areas Covered

1. What is Plasmolysis
– Definition, Mechanism, Result
2. What is Deplasmolysis
– Definition, Mechanism, Result
3. What are the Similarities Between Plasmolysis and Deplasmolysis
– Outline of Common Features
4. What is the Difference Between Plasmolysis and Deplasmolysis
– Comparison of Key Differences

Key Terms: Concave Plasmolysis, Convex Plasmolysis, Deplasmolysis, Hypotonic Solutions, Hypertonic Solutions, Plasmolysis, Turgor Pressure

What is Plasmolysis

Plasmolysis refers to the shrinking and separation of the cell membrane from the cell wall due to exosmosis. It occurs when the cells are placed in a hypertonic solution. Hypertonic solutions contain high solute concentrations. Since the water potential is high in the cytoplasm than that of the surrounding solution, water moves out of the cell. This leads to the loss of turgor pressure. Turgor pressure is the force that pushes the plasma membrane against the cell wall. At some point, the cell peels away from the cell wall due to the persisting loss of turgor pressure. This leaves gaps between the cell wall and the cell membrane, shrinking and crumpling the cell. The cytoplasm of the shrunken Rhoeo cells is shown in pink color in figure 1.

Main Difference - Plasmolysis vs Deplasmolysis

Figure 1: Convex Plasmolysis

Two types of plasmolysis may occur depending on the type of cells and the viscosity of the cytoplasm: convex plasmolysis and concave plasmolysis. In convex plasmolysis, the cytoplasm is rounded up to form convex ends. In concave plasmolysis, the separation of the cytoplasm produces concave pockets. Plasmolysis is a reversible process that can be replaced by placing the cell in a hypotonic solution. The persisting plasmolysis may lead to cytorrhysis – the complete collapse of the cell wall, leading to the death of the cell.

What is Deplasmolysis

Deplasmolysis refers to the reverse of plasmolysis by which the normal size of the protoplasm is established by the entrance of water into the cell by endosmosis. Thus, deplasmolysis is the swelling of a plasmolyzed cell. It occurs when the cell is placed in a hypotonic solution. Water moves into the cell by endosmosis since the water potential of the surrounding solution is higher than that of the cytoplasm.

Difference Between Plasmolysis and Deplasmolysis

Figure 2: Deplasmolysis

Isotonic solutions contain similar solute concentrations in the cytoplasm of a normal cell. Thus, neither plasmolysis nor deplasmolysis occurs in isotonic solutions.

Similarities Between Plasmolysis and Deplasmolysis

Both plasmolysis and deplasmolysis are two types of processes that occur during osmosis.
Both plasmolysis and deplasmolysis may destroy the cell membrane.

Definition

Plasmolysis: Plasmolysis refers to the shrinking and separation of the cell membrane from the cell wall due to the exosmosis.

Deplasmolysis: Deplasmolysis refers to the entrance of water into a plasmolysed plant cell, causing the cell membrane to return to the cell wall.

Movement of Water

Plasmolysis: Water molecules move out of the cell during plasmolysis.

Deplasmolysis: Water molecules move into the cell during plasmolysis.

Type of Osmosis

Plasmolysis: Plasmolysis occurs during exosmosis.

Deplasmolysis: Deplasmolysis occurs during endosmosis.

Type of Solutions

Plasmolysis: Plasmolysis occurs when cells are placed in a hypertonic solution.

Deplasmolysis: Deplasmolysis occurs when cells are placed in a hypotonic solution.

Solute Concentration of the Surroundings

Plasmolysis: Plasmolysis occurs when the solute concentration of the surrounding solution is higher than that of the cytoplasm.

Deplasmolysis: Deplasmolysis occurs when the solute concentration of the surrounding solution is less than that of the cytoplasm.

Water Potential

Plasmolysis: Plasmolysis occurs when the water potential of the surrounding solution is less than that of the cytoplasm.

Deplasmolysis: Deplasmolysis occurs when the water potential of the surrounding solution is higher than that of the cytoplasm.

Result

Plasmolysis: The cells may shrink due to plasmolysis.

Deplasmolysis: The cells may swell due to deplasmolysis.

Osmotic Pressure

Plasmolysis: The osmotic pressure of the cell is very low in plasmolysis.

Deplasmolysis: The osmotic pressure of the cell is high in deplasmolysis.

Conclusion

Plasmolysis and deplasmolysis are two events that occur due to the movement of water across the cell membrane by osmosis. In plasmolysis, water moves out of the cell, shrinking the protoplasm. In deplasmolysis, water moves into the cells, swelling the protoplasm. Plasmolysis occurs in hypertonic solutions while deplasmolysis occurs in hypotonic solutions. The main difference between plasmolysis and deplasmolysis is the direction of the movement of water in each event.

Reference:

1. Lang, Ingeborg, et al. “Plasmolysis: Loss of Turgor and Beyond.” Plants, MDPI, Dec. 2014, Available here.
2.“Plasmolysis.” Wikipedia, Wikimedia Foundation, 11 Dec. 2017, Available here.

Image Courtesy:

1. “Rhoeo Discolor – Plasmolysis” By Mnolf – Photo taken in Innsbruck, Austria (CC BY-SA 3.0) via Commons Wikimedia
2. “Деплазмолиз клетки” By KsuyshaWinter 1 – Own work (CC BY-SA 4.0) via Commons Wikimedia