Plasmolysis

Plant cell and animal cell both are eukaryotic, still there are various differences between them; whether it is the presence of cell walls in plants or the varying size of vacuole. These differences are a clear indication of the variation in their functions and the processes these cells go through. One of these essential processes is Plasmolysis. Now, the question is, what is plasmolysis, and how can it be defined in science?

What is Plasmolysis

Plasmolysis is the process by which a plant cell loses water when placed in a hypertonic solution(a solution having a higher amount of solutes than the cell). The actual process behind this is the movement of water outwards due to osmosis, resulting in the shrinkage of the entire cell. As osmosis requires zero energy, Plasmolysis becomes an out-of-control process, even though excessive water loss can lead to the collapse of the cell wall. 

Types of Plasmolysis

One can easily deduce Plasmolysis has occurred by looking at the gap between the cell wall and the plasma membrane. Well, there are two types of Plasmolysis based on the appearance of protoplasmic shrinking : Concave and convex plasmolysis.

Concave Plasmolysis-  In this, both the protoplasm and the plasma membrane shrinks and detaches from the cell wall. Due to the detachment of protoplasm( then called protoplast), a 'half-moon-shape' is formed in the cell. Nonetheless, concave plasmolysis can be reversed by placing the cell in a hypotonic solution.

Convex Plasmolysis- This is an irreversible process. The excessive loss of water from the cell loosens the plasma membrane and protoplasts, leading to the detachment from the cell wall. As this process cannot be reversed, it results in the destruction of the cell. Hence, this is what happens when a plant withers and dies from lack of water.

Plasmolysis Process

The complete process of plasmolysis can be understood in three stages.

Stage1- This is the initial stage of the process when the cell starts losing the water, the size of the cell decreases, and the cell wall can be identified.

Stage2- This is the second stage when the cell has reached its maximum level of contraction, and the cytoplasm gets detached from the cell wall, becoming spherical.

Stage3- In the final stage, the cytoplasm completely detaches from the cell wall and lies in the center. 

This entire process can be better understood by the plasmolysis diagram below. On the left is a cell placed in Isotonic solution( a solution having an equal amount of solute to that of the cell), and on the right is the plasmolyzed cell. You can quickly note the difference in the shape of cytoplasm in both of these diagrams mentioned below.

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Plasmolysis Examples

Plasmolysis takes place in the extreme loss of water from the cell, and this makes it a rare occurrence naturally. It can be witnessed when the plants are exposed to coastal flooding or chemical weedicides. Few common plasmolysis examples include  the shrinking of the food and pickle that we put in excessive salts to preserve them.

FAQ (Frequently Asked Questions)

1. What is the Significance of Plasmolysis?

Plasmolysis is the process in which the cells lose water through osmosis when placed in a hypertonic solution. Through this, we can understand the process of osmosis rightly and distinguish the semi-permeable nature of the cell wall.

2. Why is Plasmolysis Harmful to the Call?

Water rushes out of the cell, right after they are placed in the hypertonic solution, and the cell starts shrinking. These plasmolyzed cells are dehydrated and are then devoid of all physiological functions, sometimes leading to the death of the plant.

3. Is Plasmolysis a Process Associated only with Plants?

Yes, Plasmolysis occurs only in plants because only plants have a cell wall. Animal cells only have cell membranes, no cell wall.

4. How is Plasmolysis Essential for Food Preservation and Storage?

Plasmolysis plays a vital role in food preservation and storage. We add salt to preserve the meat, jam, jellies or pickle, etc. that increase the osmotic pressure of the food, thus plasmolyzing the bacteria and Fungi. 

5. What is Turgidity in a Plant Cell? 

Turgidity is the swollen state of a plant and helps a plant to stand upright. Now you know what plasmolysis is. Turgidity and plasmolysis are the results of the osmotic movement of water because of different concentrations of solutes. In simple words, more is the turgidity, more rigidly the plant stands.

6. What is the Main Difference Between Both Types of Plasmolysis?

The two types are: Convex and concave. They both differ in the shape the cytoplasm makes once the cell loses water. Another significant difference is that the concave Plasmolysis is reversible, while convex Plasmolysis is not.