Plasmolysis – Definition, Types, Stages, Examples

Plasmolysis occurs when cells are exposed to a hypertonic solution. If the cell is in a hypotonic solution, which results in a reduced external osmotic pressure and a net flow of water into the cell, the reverse process, deplasmolysis or cytolysis, might happen. It is feasible to ascertain the tonicity of the cell’s surroundings and the pace at which solute molecules traverse the cellular membrane by observing plasmolysis and deplasmolysis.

Eukaryotic plant cells are made up of specialized cellular organelles and differ fundamentally from animal cells in a number of ways. Typically, plant cells have a thick cell wall to hold them upright and keep them from losing their form. The cytoplasm, plasma membrane, and all other cell organelles work together to maintain the plant’s activity. The water in the plant cell is kept in the vacuoles, an organelle with a membrane enclosing fluid. Under certain circumstances, plant cells either do not receive enough water or experience a significant loss of water. This causes the plant cell to completely contract, and the phenomenon is known as plasmolysis.

What is Plasmolysis?

Plasmolysis is described as the removal or contraction of a plant cell’s cellular constituents due to water loss. The name “plasmolysis” comes from the Greek word “lysis,” which means “loosening,” and the Latin word “plasma,” which means “matrix.” Plasmolysis is an uncommon occurrence in nature and only happens under extreme circumstances. In the laboratory, it is induced by immersing cells in strong saline or sugar (sucrose) solutions to cause exosmosis, frequently employing Elodea plants or onion epidermal cells with colored cell sap to make the process visible. Plant cells can be stained with methylene blue.

Stages of Plasmolysis

There are three distinct steps to the entire plasmolysis process:

1. Incipient Plasmolysis: Water begins to flow out of the cell during the incipient plasmolysis stage, which also marks the beginning of the cell’s volume reduction and the appearance of the cell wall.
2. Evident or Limiting Plasmolysis: This is the second step of plasmolysis when the cell wall’s ability to contract has been exhausted and the cytoplasm separates from the cell wall to take on a spherical shape.
3. Final Plasmolysis: This is the third and final stage of plasmolysis. During this stage, the cytoplasm entirely separates from the cell wall and stays in the core of the cell.

Movement of Water through Plasma Membrane 

The cell membrane isolates the interiors of the cell from its surroundings during the Plasmolysis process within the plant cell. It permits certain particles to pass the membrane, such as water molecules, ions, and other picky particles, while preventing the passage of others. Cell membranes allow water molecules to enter and exit the cell, and this water flow is a required result that permits cells to obtain water.

By submerging a living cell in a potent salt solution, the laboratory procedure of plasmolysis can be clearly demonstrated. Water from the cell sap travels out of the plant cells when they are submerged in the concentrated salt solution due to osmosis. Water enters the surrounding medium by passing through the cell membrane as a result. Protoplasm eventually becomes detached from the cell and develops a spherical shape.

Plasmolysis

Types of Plasmolysis

There are two distinct forms of plasmolysis, and this division is primarily based on the cytoplasm’s ultimate structure.

Concave Plasmolysis

The lack of water causes the cell membrane and protoplasm to contract and start to separate from the cell wall during concave plasmolysis. Concave plasmolysis is a process that may be reversed, and it can be done so by submerging the cell in a hypotonic solution, which encourages the cell to take up water once more.

Convex Plasmolysis

Convex plasmolysis induces both the protoplasm and membrane of a cell to dissipate excessive water that they totally separate from the cell wall. The cell is ultimately destroyed when the cell wall gives way. Convex plasmolysis, which is irreversible like concave plasmolysis, occurs when a plant dies out from a lack of water. Compared to convex plasmolysis, this kind of plasmolysis is more difficult.

Examples of Plasmolysis 

Plasmolysis happens with greater frequency and in greater amounts of water loss. Examples of plasmolysis in everyday situations involve the following:

1. Ocean water dumps salt onto land during severe coastal flooding due to plasmolysis.
2. Weeds are eliminated from lawns, orchards, and agricultural areas through weedicide spraying. Plasmolysis, a natural phenomenon, is responsible for this.
3. Vegetables shrink when they are in a hypertonic environment.
4. When exposed to hypertonic circumstances, blood cells contract.
5. When foods like jams, jellies, and pickles have more salt added to them as preservatives. As the outside concentration increases, the cells lose water and lose their ability to support microbial development.

Deplasmolysis 

Due to the larger concentration of water outside the cell, water enters the plasmolyzed cell when it is placed in a hypotonic solution (a solution in which the solute concentration is less than the cell sap). The cell then enlarges and stiffens which is known as Deplasmolysis. Water does not flow inside or outside of live cells when they are placed in an isotonic solution (both solutions have an identical amount of solute particles). The cells are referred to as flaccid because water is moving in and out of them in an equilibrium state.

FAQs on Plasmolysis

Q1: What is Concave Plasmolysis?

Answer:

Concave plasmolysis is a process that may be reversed, and it can be done so by submerging the cell in a hypotonic solution, which encourages the cell to take up water once more.

Q2: What are the 3 stages of Plasmolysis?

Answer:

The three stages of Plasmolysis are: Incipient Plasmolysis, Evident Plasmolysis, and Final Plasmolysis.

Q3: Define the term Deplasmolysis.

Answer:

Due to the larger concentration of water outside the cell, water enters the plasmolyzed cell when it is placed in a hypotonic solution. The cell then enlarges and stiffens which is known as Deplasmolysis.

Q4: What happens in the final stage of Plasmolysis?

Answer:

During the third and final stage of plasmolysis, the cytoplasm entirely separates from the cell wall and stays in the core of the cell.